#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
//!===========================================================!//
//!  dP     dP                          dP                    !//
//!  88     88                          88                    !//
//!  88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b.  !//
//!  88     88  88ooood8 88'  '88 88'  '88 88ooood8 88'  '88  !//
//!  88     88  88.  ... 88.  .88 88.  .88 88.  ... 88        !//
//!  dP     dP  '88888P' '88888P8 '88888P8 '88888P' dP        !//
//!===========================================================!//
using ld = long double;
using ll = long long;
using ull = unsigned long long;
std::mt19937 mt{std::random_device{}()};
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename T>
constexpr T MOD = static_cast<T>(1000000007);
template <typename F>
constexpr F PI() { return 3.1415926535897932385; }
#define SHOW(...) (std::cerr << "(" << #__VA_ARGS__ << ") = ("), HogeHogeSansuu(__VA_ARGS__), std::cerr << ")" << std::endl;
struct has_debugPrint_impl
{
    template <class T>
    static auto check(T&& x) -> decltype(x.debugPrint(), std::true_type{});
    template <class T>
    static auto check(...) -> std::false_type;
};
template <class T>
class has_debugPrint : public decltype(has_debugPrint_impl::check<T>(std::declval<T>()))
{
};
template <bool>
struct HogeHogeDump
{
    template <typename T>
    static void dump(const T& x) { x.debugPrint(); }
};
template <>
struct HogeHogeDump<false>
{
    template <typename T>
    static void dump(const T& x) { std::cerr << x; }
};
void HogeHogeSansuu() { ; }
template <typename T>
void HogeHogeSansuu(const T& x) { HogeHogeDump<has_debugPrint<T>::value>::dump(x); }
template <typename T, typename... Args>
void HogeHogeSansuu(const T& x, Args... args) { HogeHogeDump<has_debugPrint<T>::value>::dump(x), std::cerr << ",", HogeHogeSansuu(args...); }
template <typename T>
bool chmin(T& a, const T& b) { return a = std::min(a, b), a == b; }
template <typename T>
bool chmax(T& a, const T& b) { return a = std::max(a, b), a == b; }
template <typename T, typename F>
void For(const T s, const T t, const F f)
{
    for (T i = s; i != t; i += T(s < t ? 1 : -1)) { f(i); }
}
template <typename T, typename F>
void Rep(const T N, const F f) { For<T, F>(0, N, f); }
template <typename T, typename F>
void RRep(const T N, const F f) { For<T, F>(N - 1, -1, f); }
template <typename T>
std::vector<T> Vec(const std::size_t n, T v) { return std::vector<T>(n, v); }
template <class... Args>
auto Vec(const std::size_t n, Args... args) { return std::vector<decltype(Vec(args...))>(n, Vec(args...)); }
template <typename T>
constexpr T PopCount(const T u)
{
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL), v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL), v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL, static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
}
template <typename T>
constexpr T log2p1(const T u)
{
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2), v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32), PopCount(v);
}
template <typename T>
constexpr bool ispow2(const T v) { return (v << 1) == (T(1) << (log2p1(v))); }
template <typename T>
constexpr T ceil2(const T v) { return ispow2(v) ? v : T(1) << log2p1(v); }
template <typename T>
constexpr T floor2(const T v) { return v == 0 ? T(0) : ispow2(v) ? v : T(1) << (log2p1(v) - 1); }
template <typename T>
struct Accum
{
    template <typename InIt>
    Accum(const InIt first, const InIt last) : accum(std::size_t(std::distance(first, last))) { std::partial_sum(first, last, accum.begin()); }
    T sum(const std::size_t i) const { return i == 0 ? T(0) : accum[i - 1]; }
    T sum(const std::size_t l, const std::size_t r) const { return sum(r) - sum(l); }
    std::vector<T> accum;
};
template <typename T>
struct Accum2D
{
    Accum2D(const std::vector<std::vector<T>>& t) : accum{t}
    {
        for (std::size_t i = 0; i < accum.size(); i++) {
            for (std::size_t j = 1; j < accum[i].size(); j++) { accum[i][j] += accum[i][j - 1]; }
        }
        for (std::size_t i = 1; i < accum.size(); i++) {
            for (std::size_t j = 0; j < accum[i].size(); j++) { accum[i][j] += accum[i - 1][j]; }
        }
    }
    T sum(const std::size_t y, const std::size_t x) const { return y == 0 or x == 0 ? T(0) : accum[y - 1][x - 1]; }
    T sum(const std::size_t ymin, const std::size_t ysup, const std::size_t xmin, const std::size_t xsup) const { return sum(ysup, xsup) - sum(ymin, xmin); }
    std::vector<std::vector<T>> accum;
};
template <typename T>
struct Zip
{
    template <typename InIt>
    Zip(const InIt first, const InIt last) : unzip(std::size_t(std::distance(first, last)))
    {
        std::copy(first, last, unzip), std::sort(unzip.begin(), unzip.end()), unzip.erase(std::unique(unzip.begin(), unzip.end()), unzip.end());
        for (std::size_t i = 0; i < unzip.size(); i++) { zip[unzip[i]] = i; }
    }
    std::vector<T> unzip;
    std::map<T, std::size_t> zip;
};
template <typename T, std::size_t N>
std::ostream& operator<<(std::ostream& os, const std::array<T, N>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename T, typename A>
std::ostream& operator<<(std::ostream& os, const std::deque<T, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename K, typename T, typename C, typename A>
std::ostream& operator<<(std::ostream& os, const std::multimap<K, T, C, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << "<" << e.first << ": " << e.second << ">,"; }
    return (os << "]" << std::endl);
}
template <typename T, typename C, typename A>
std::ostream& operator<<(std::ostream& os, const std::multiset<T, C, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename K, typename T, typename C, typename A>
std::ostream& operator<<(std::ostream& os, const std::map<K, T, C, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << "<" << e.first << ": " << e.second << ">,"; }
    return (os << "]" << std::endl);
}
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, const std::pair<T1, T2>& v) { return (os << "<" << v.first << "," << v.second << ">"); }
template <typename T1, typename T2, typename T3>
std::ostream& operator<<(std::ostream& os, const std::priority_queue<T1, T2, T3>& v)
{
    auto q = v;
    os << "[";
    while (not q.empty()) { os << q.top() << ",", q.pop(); }
    return os << "]\n";
}
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, const std::queue<T1>& v)
{
    auto q = v;
    os << "[";
    while (not q.empty()) { os << q.front() << ",", q.pop(); }
    return os << "]\n";
}
template <typename T, typename C, typename A>
std::ostream& operator<<(std::ostream& os, const std::set<T, C, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, const std::stack<T1>& v)
{
    auto q = v;
    os << "[";
    while (not q.empty()) { os << q.top() << ",", q.pop(); }
    return os << "]\n";
}
template <typename K, typename T, typename H, typename P, typename A>
std::ostream& operator<<(std::ostream& os, const std::unordered_multimap<K, T, H, P, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << "<" << e.first << ": " << e.second << ">,"; }
    return (os << "]" << std::endl);
}
template <typename T, typename H, typename P, typename A>
std::ostream& operator<<(std::ostream& os, const std::unordered_multiset<T, H, P, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename K, typename T, typename H, typename P, typename A>
std::ostream& operator<<(std::ostream& os, const std::unordered_map<K, T, H, P, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << "<" << e.first << ": " << e.second << ">,"; }
    return (os << "]" << std::endl);
}
template <typename T, typename H, typename P, typename A>
std::ostream& operator<<(std::ostream& os, const std::unordered_set<T, H, P, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
template <typename T, typename A>
std::ostream& operator<<(std::ostream& os, const std::vector<T, A>& v)
{
    os << "[";
    for (const auto& e : v) { os << e << ","; }
    return (os << "]" << std::endl);
}
//!===============================================================!//
//!   88888888b            dP       .88888.   a88888b. 888888ba   !//
//!   88                   88      d8'   '88 d8'   '88 88    '8b  !//
//!  a88aaaa    dP.  .dP d8888P    88        88        88     88  !//
//!   88         '8bd8'    88      88   YP88 88        88     88  !//
//!   88         .d88b.    88      Y8.   .88 Y8.   .88 88    .8P  !//
//!   88888888P dP'  'dP   dP       '88888'   Y88888P' 8888888P   !//
//!===============================================================!//
template <typename T>
constexpr std::pair<T, T> extgcd(const T a, const T b)
{
    if (b == 0) { return std::pair<T, T>{1, 0}; }
    const auto p = extgcd(b, a % b);
    return {p.second, p.first - p.second * (a / b)};
}
template <typename T>
constexpr T inverse(const T a, const T mod) { return (mod + extgcd((mod + a % mod) % mod, mod).first % mod) % mod; }
//!========================================================!//
//!  8888ba.88ba                 dP    dP            dP    !//
//!  88  '8b  '8b                88    88            88    !//
//!  88   88   88 .d8888b. .d888b88    88 88d888b. d8888P  !//
//!  88   88   88 88'  '88 88'  '88    88 88'  '88   88    !//
//!  88   88   88 88.  .88 88.  .88    88 88    88   88    !//
//!  dP   dP   dP '88888P' '88888P8    dP dP    dP   dP    !//
//!========================================================!//
template <typename T, T mod>
class ModInt
{
private:
    T value;

public:
    ModInt() : value{0} {}
    ModInt(const T val) : value{((val % mod) + mod) % mod} {}
    ModInt(const ModInt<T, mod>& n) : value{n()} {}
    ModInt<T, mod>& operator=(const ModInt<T, mod>& n) { return value = n(), (*this); }
    ModInt<T, mod>& operator=(const T v) { return value = (mod + v % mod) % mod, (*this); }
    ModInt<T, mod> operator+() const { return *this; }
    ModInt<T, mod> operator-() const { return ModInt{mod - value}; }
    ModInt<T, mod> operator+(const ModInt<T, mod>& val) const { return ModInt{value + val()}; }
    ModInt<T, mod> operator-(const ModInt<T, mod>& val) const { return ModInt{value - val() + mod}; }
    ModInt<T, mod> operator*(const ModInt<T, mod>& val) const { return ModInt{value * val()}; }
    ModInt<T, mod> operator/(const ModInt<T, mod>& val) const { return ModInt{value * inverse(val(), mod)}; }
    ModInt<T, mod>& operator+=(const ModInt<T, mod>& val) { return (((value += val()) %= mod) += mod) %= mod, (*this); }
    ModInt<T, mod>& operator-=(const ModInt<T, mod>& val) { return (((value -= val()) %= mod) += mod) %= mod, (*this); }
    ModInt<T, mod>& operator*=(const ModInt<T, mod>& val) { return (((value *= val()) %= mod) += mod) %= mod, (*this); }
    ModInt<T, mod>& operator/=(const ModInt<T, mod>& val) { return (((value *= inverse(val(), mod)) %= mod) += mod) %= mod, (*this); }
    ModInt<T, mod> operator+(const T val) const { return ModInt{value + val}; }
    ModInt<T, mod> operator-(const T val) const { return ModInt{value - val}; }
    ModInt<T, mod> operator*(const T val) const { return ModInt{value * val}; }
    ModInt<T, mod> operator/(const T val) const { return ModInt{value * inverse(val, mod)}; }
    template <typename I>
    ModInt<T, mod> operator^(const I n) const { return n < 0 ? (T(1) / (*this)) ^ (-n) : n == 0 ? ModInt<T, mod>(1) : n % 2 == 1 ? (*this) * ((*this) ^ (n - 1)) : ((*this * *this) ^ (n / 2)); }
    ModInt<T, mod>& operator+=(const T val) { return (((value += val) %= mod) += mod) %= mod, (*this); }
    ModInt<T, mod>& operator-=(const T val) { return (((value -= val) %= mod) += mod) %= mod, (*this); }
    ModInt<T, mod>& operator*=(const T val) { return (((value *= val) %= mod) += mod) %= mod, (*this); }
    ModInt<T, mod>& operator/=(const T val) { return (((value *= inverse(val, mod)) %= mod) += mod) %= mod, (*this); }
    template <typename I>
    ModInt<T, mod>& operator^=(const I n) { return (*this) = ((*this) ^ n); }
    bool operator==(const ModInt<T, mod>& val) const { return value == val.value; }
    bool operator!=(const ModInt<T, mod>& val) const { return not(*this == val); }
    bool operator==(const T val) const { return value == (mod + val % mod) % mod; }
    bool operator!=(const T val) const { return not(*this == val); }
    T operator()() const { return value; }
};
template <typename T, T mod>
inline ModInt<T, mod> operator+(const T val, const ModInt<T, mod>& n) { return ModInt<T, mod>{n() + val}; }
template <typename T, T mod>
inline ModInt<T, mod> operator-(const T val, const ModInt<T, mod>& n) { return ModInt<T, mod>{-n() + val}; }
template <typename T, T mod>
inline ModInt<T, mod> operator*(const T val, const ModInt<T, mod>& n) { return ModInt<T, mod>{n() * val}; }
template <typename T, T mod>
inline ModInt<T, mod> operator/(const T val, const ModInt<T, mod>& n) { return ModInt<T, mod>(val) / n; }
template <typename T, T mod>
inline bool operator==(const T val, const ModInt<T, mod>& n) { return n == val; }
template <typename T, T mod>
inline bool operator!=(const T val, const ModInt<T, mod>& n) { return not(val == n); }
template <typename T, T mod>
inline std::istream& operator>>(std::istream& is, ModInt<T, mod>& n)
{
    T v;
    return is >> v, n = v, is;
}
template <typename T, T mod>
std::ostream& operator<<(std::ostream& os, const ModInt<T, mod>& n) { return (os << n()); }
template <int mod>
using Mint = ModInt<int, mod>;
template <ll mod>
using Mll = ModInt<ll, mod>;
//!============================================================================!//
//!  8888ba.88ba                 dP     a88888b.                     dP        !//
//!  88  '8b  '8b                88    d8'   '88                     88        !//
//!  88   88   88 .d8888b. .d888b88    88        .d8888b. 88d8b.d8b. 88d888b.  !//
//!  88   88   88 88'  '88 88'  '88    88        88'  '88 88''88''88 88'  '88  !//
//!  88   88   88 88.  .88 88.  .88    Y8.   .88 88.  .88 88  88  88 88.  .88  !//
//!  dP   dP   dP '88888P' '88888P8     Y88888P' '88888P' dP  dP  dP 88Y8888'  !//
//!============================================================================!//
template <typename T, T mod>
class ModComb
{
public:
    ModComb(const std::size_t N) : f(N + 1, ModInt<T, mod>(1)), in(N + 1, ModInt<T, mod>(1)), invf(N + 1, ModInt<T, mod>(1))
    {
        for (T i = 2; i <= (T)N; i++) { f[i] = f[i - 1] * i, in[i] = (mod - (mod / i)) * in[mod % i], invf[i] = invf[i - 1] * in[i]; }
    }
    ModInt<T, mod> fact(const std::size_t N) const { return f[N]; }
    ModInt<T, mod> inv(const std::size_t N) const { return in[N]; }
    ModInt<T, mod> invFact(const std::size_t N) const { return invf[N]; }
    ModInt<T, mod> perm(const std::size_t N, const std::size_t K) const { return f[N] * invf[N - K]; }
    ModInt<T, mod> comb(const std::size_t N, const std::size_t K) const { return f[N] * invf[K] * invf[N - K]; }

private:
    std::vector<ModInt<T, mod>> f, in, invf;
};
//!==================================!//
//!   88888888b  88888888b d888888P  !//
//!   88         88           88     !//
//!  a88aaaa    a88aaaa       88     !//
//!   88         88           88     !//
//!   88         88           88     !//
//!   dP         dP           dP     !//
//!==================================!//
template <std::size_t L = 20, typename F = double>
class FFT
{
public:
    struct C
    {
        F x{}, y{};
        C operator+(const C& c) const { return C{x + c.x, y + c.y}; }
        C operator-(const C& c) const { return C{x - c.x, y - c.y}; }
        C operator*(const C& c) const { return C{x * c.x - y * c.y, x * c.y + y * c.x}; }
        C operator~() const { return C{x, -y}; }
    };

private:
    //! static inline 使わせてくれ !//
    static C roots[1 << L];
    static std::size_t rev[1 << L];
    static C fa[1 << L], fb[1 << L];
    void fft(C* a, const std::size_t n) const
    {
        const std::size_t shift = L - n;
        for (std::size_t i = 0; i < (1UL << n); i++) {
            if (i < (rev[i] >> shift)) { std::swap(a[i], a[rev[i] >> shift]); }
        }
        for (std::size_t k = 1; k < (1UL << n); k <<= 1) {
            for (std::size_t i = 0; i < (1UL << n); i += (2 * k)) {
                for (std::size_t j = 0; j < k; j++) {
                    const C z = a[i + j + k] * roots[j + k];
                    a[i + j + k] = a[i + j] - z, a[i + j] = a[i + j] + z;
                }
            }
        }
    }
    static std::size_t LG(const std::size_t n)
    {
        std::size_t lg = 0;
        for (std::size_t ans = 1; ans < n; ans <<= 1, lg++) {}
        return lg;
    }

public:
    FFT()
    {
        for (std::size_t i = 0; i < (1 << L); i++) { rev[i] = (rev[i >> 1] >> 1) + ((i & 1) << (L - 1)); }
        for (std::size_t k = 1; k < L; k++) {
            const F s = 2 * PI<F>() / (1 << (k + 1));
            for (std::size_t i = 1UL << (k - 1); i < (1UL << k); i++) { roots[i << 1] = roots[i], roots[i << 1 | 1] = roots[i << 1] * C{std::cos(s), std::sin(s)}; }
        }
    }
    template <typename T = ll, typename O = int>
    std::vector<T> convolute(const std::vector<O>& a, const std::vector<O>& b)
    {
        const std::size_t need = a.size() + b.size() - 1, lg = LG(need), sz = 1 << lg;
        for (std::size_t i = 0; i < sz; i++) { fa[i] = C{F(i < a.size() ? a[i] : 0), F(i < b.size() ? b[i] : 0)}; }
        fft(fa, lg);
        const C r{0, -0.25 / (F)sz};
        for (std::size_t i = 0; i <= (sz >> 1); i++) {
            std::size_t j = (sz - i) & (sz - 1);
            const C z = (fa[j] * fa[j] - ~(fa[i] * fa[i])) * r;
            fa[j] = (fa[i] * fa[i] - ~(fa[j] * fa[j])) * r, fa[i] = z;
        }
        fft(fa, lg);
        std::vector<T> ans(need);
        for (std::size_t i = 0; i < need; i++) { ans[i] = (T)std::floor(fa[i].x + 0.5); }
        return ans;
    }
    template <typename T = int, typename O = int>
    std::vector<T> convolute(const std::vector<O>& a, const std::vector<O>& b, const T mod)
    {
        const std::size_t need = a.size() + b.size() - 1, lg = LG(need), sz = 1 << lg;
        for (std::size_t i = 0; i < a.size(); i++) {
            const T x = (mod + a[i] % mod) % mod;
            fa[i] = C{(F)(x & ((1 << 15) - 1)), F(x >> 15)};
        }
        std::fill(fa + a.size(), fa + sz, C{0, 0});
        fft(fa, lg);
        for (std::size_t i = 0; i < b.size(); i++) {
            const T x = (mod + b[i] % mod) % mod;
            fb[i] = C{F(x & ((1 << 15) - 1)), F(x >> 15)};
        }
        std::fill(fb + b.size(), fb + sz, C{0, 0});
        fft(fb, lg);
        F ratio = 0.25 / F(sz);
        C r2{0, -1}, r3{ratio, 0}, r4{0, -ratio}, r5{0, 1};
        for (std::size_t i = 0; i <= (sz >> 1); i++) {
            const std::size_t j = (sz - i) & (sz - 1);
            const C a1 = (fa[i] + ~fa[j]), a2 = (fa[i] - ~fa[j]) * r2, b1 = (fb[i] + ~fb[j]) * r3, b2 = (fb[i] - ~fb[j]) * r4;
            if (i != j) {
                const C c1 = (fa[j] + ~fa[i]), c2 = (fa[j] - ~fa[i]) * r2, d1 = (fb[j] + ~fb[i]) * r3, d2 = (fb[j] - ~fb[i]) * r4;
                fa[i] = c1 * d1 + c2 * d2 * r5, fb[i] = c1 * d2 + c2 * d1;
            }
            fa[j] = a1 * b1 + a2 * b2 * r5, fb[j] = a1 * b2 + a2 * b1;
        }
        fft(fa, lg), fft(fb, lg);
        std::vector<T> ans(need);
        for (std::size_t i = 0; i < need; i++) {
            const T aa = (T)std::floor(fa[i].x + 0.5), bb = (T)std::floor(fb[i].x + 0.5), cc = (T)std::floor(fa[i].y + 0.5);
            ans[i] = (T)(aa + ((bb % mod) << 15) + ((cc % mod) << 30)) % mod;
        }
        return ans;
    }
};
//! static inline 使わせてくれマジで !//
template <std::size_t L, typename F>
typename FFT<L, F>::C FFT<L, F>::roots[1 << L] = {{0, 0}, {1, 0}};
template <std::size_t L, typename F>
std::size_t FFT<L, F>::rev[1 << L] = {0, 1};
template <std::size_t L, typename F>
typename FFT<L, F>::C FFT<L, F>::fa[1 << L];
template <std::size_t L, typename F>
typename FFT<L, F>::C FFT<L, F>::fb[1 << L];
//!============================================!//
//!    8888ba.88ba             oo              !//
//!    88  '8b  '8b                            !//
//!    88   88   88  .d8888b.  dP  88d888b.    !//
//!    88   88   88  88'  '88  88  88'  '88    !//
//!    88   88   88  88.  .88  88  88    88    !//
//!    dP   dP   dP  '88888P8  dP  dP    dP    !//
//!============================================!//

int main()
{
    int N, M, D1, D2;
    std::cin >> N >> M >> D1 >> D2;
    if (M - (ll)D1 * (N - 1) < 1) { return std::cout << 0 << std::endl, 0; }
    const int D = D2 - D1, L = M - D1 * (N - 1) - 1;
    ModComb<ll, MOD<ll>> mod(L + N);
    std::vector<int> a(L + 1), b(L + 1);
    for (int i = 0; i * (D + 1) <= L and i < N; i++) { a[i * (D + 1)] = (int)(mod.comb(N - 1, i) * (i % 2 == 0 ? 1 : -1))(); }
    for (int i = 0; i <= L; i++) { b[i] = (int)mod.comb(i + N - 2, N - 2)(); }
    FFT<21> fft;
    auto c = fft.convolute(a, b, MOD<ll>);
    ll sum = 0;
    for (int i = 0; i <= L; i++) { (sum += (ll)(L - i + 1) * c[i] % MOD<ll>) %= MOD<ll>; }
    std::cout << sum << std::endl;
    return 0;
}