// >>> TEMPLATES #include using namespace std; using ll = long long; using ld = long double; using i32 = int32_t; using i64 = int64_t; #define int ll #define double ld #define rep(i,n) for (int i = 0; i < (int)(n); i++) #define rep1(i,n) for (int i = 1; i <= (int)(n); i++) #define repR(i,n) for (int i = (int)(n)-1; i >= 0; i--) #define rep1R(i,n) for (int i = (int)(n); i >= 1; i--) #define loop(i,a,B) for (int i = a; i B; i++) #define loopR(i,a,B) for (int i = a; i B; i--) #define all(x) (x).begin(), (x).end() #define allR(x) (x).rbegin(), (x).rend() #define pb push_back #define eb emplace_back #define mp make_pair #define fst first #define snd second auto constexpr INF32 = numeric_limits::max()/2-1; auto constexpr INF64 = numeric_limits::max()/2-1; auto constexpr INF = numeric_limits::max()/2-1; #ifdef LOCAL #include "debug.hpp" #define dump(...) cerr << "[" << setw(3) << __LINE__ << ":" << __FUNCTION__ << "] ", dump_impl(#__VA_ARGS__, __VA_ARGS__) #define say(x) cerr << "[" << __LINE__ << ":" << __FUNCTION__ << "] " << x << endl #define debug if (1) #else #define dump(...) (void)(0) #define say(x) (void)(0) #define debug if (0) #endif template using pque_max = priority_queue; template using pque_min = priority_queue, greater >; template ::value>::type> ostream& operator<<(ostream& os, T const& v) { bool f = true; for (auto const& x : v) os << (f ? "" : " ") << x, f = false; return os; } template ::value>::type> istream& operator>>(istream& is, T &v) { for (auto& x : v) is >> x; return is; } template istream& operator>>(istream& is, pair& p) { return is >> p.first >> p.second; } struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup; template struct FixPoint : private F { constexpr FixPoint(F&& f) : F(forward(f)) {} template constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward(x)...); } }; struct MakeFixPoint { template constexpr auto operator|(F&& f) const { return FixPoint(forward(f)); } }; #define MFP MakeFixPoint()| #define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__) template struct vec_impl { using type = vector::type>; template static type make_v(size_t n, U&&... x) { return type(n, vec_impl::make_v(forward(x)...)); } }; template struct vec_impl { using type = T; static type make_v(T const& x = {}) { return x; } }; template using vec = typename vec_impl::type; template auto make_v(Args&&... args) { return vec_impl::make_v(forward(args)...); } template void quit(T const& x) { cout << x << endl; exit(0); } template constexpr bool chmin(T& x, U const& y) { if (x > y) { x = y; return true; } return false; } template constexpr bool chmax(T& x, U const& y) { if (x < y) { x = y; return true; } return false; } template constexpr auto sumof(It b, It e) { return accumulate(b,e,typename iterator_traits::value_type{}); } template int sz(T const& x) { return x.size(); } template int lbd(C const& v, T const& x) { return lower_bound(v.begin(), v.end(), x)-v.begin(); } template int ubd(C const& v, T const& x) { return upper_bound(v.begin(), v.end(), x)-v.begin(); } template int ppt(C const& v, F f) { return partition_point(v.begin(), v.end(), f)-v.begin(); } // <<< // >>> modint template class modint { static_assert(md > 0, ""); using M = modint; using ll = int64_t; int32_t x; public: static constexpr int32_t mod = md; constexpr modint(ll x = 0) : x((x%=mod) < 0 ? x+mod : x) { } constexpr ll val() const { return x; } constexpr explicit operator ll() const { return x; } constexpr bool operator==(M const& r) const { return x == r.x; } constexpr bool operator!=(M const& r) const { return x != r.x; } constexpr M operator+() const { return *this; } constexpr M operator-() const { return M()-*this; } constexpr M& operator+=(M const& r) { ll t = ll(x) + r.x; if (t >= mod) t -= mod; x = t; return *this; } constexpr M& operator-=(M const& r) { ll t = ll(x) + mod-r.x; if (t >= mod) t -= mod; x = t; return *this; } constexpr M& operator*=(M const& r) { return *this = *this * r; } constexpr M operator*(M const& r) const { M t; t.x = (ll(x)*r.x) % mod; return t; } constexpr M& operator/=(M const& r) { return *this *= r.inv(); } constexpr M operator+(M const& r) const { return M(*this) += r; } constexpr M operator-(M const& r) const { return M(*this) -= r; } constexpr M operator/(M const& r) const { return M(*this) /= r; } friend constexpr M operator+(ll x, M const& y) { return M(x)+y; } friend constexpr M operator-(ll x, M const& y) { return M(x)-y; } friend constexpr M operator*(ll x, M const& y) { return M(x)*y; } friend constexpr M operator/(ll x, M const& y) { return M(x)/y; } constexpr M pow(ll n) const { if (n < 0) return inv().pow(-n); M v = *this, r = 1; for (; n > 0; n >>= 1, v *= v) if (n&1) r *= v; return r; } constexpr M inv() const { assert(x > 0); ll t = 1, v = x, q = 0, r = 0; while (v != 1) { q = mod / v; r = mod % v; if (r * 2 < v) { t *= -q; t %= mod; v = r; } else { t *= q + 1; t %= mod; v -= r; } } if (t < 0) t += mod; M y; y.x = t; return y; } #ifdef LOCAL friend string to_s(M r) { return to_s(r.val(), mod); } #endif friend ostream& operator<<(ostream& os, M r) { return os << r.val(); } friend istream& operator>>(istream& is, M &r) { int64_t x; is >> x; r = x; return is; } }; // <<< //constexpr int64_t MOD = 998244353; constexpr int64_t MOD = 1e9+7; using mint = modint<(int32_t)MOD>; int32_t main() { int n,d,k; cin >> n >> d >> k; vector dp(k+1); dp[0] = 1; rep (i,n) { dp.insert(dp.begin(), 0); dp.pop_back(); rep (j,dp.size()-1) dp[j+1] += dp[j]; repR (j,dp.size()) dp[j] -= dp[max(j-d,0LL)]; } cout << dp[k] << endl; }