#include using namespace std::literals::string_literals; using i64 = std::int_fast64_t; using std::cout; using std::endl; using std::cin; template std::vector make_v(size_t a){return std::vector(a);} template auto make_v(size_t a,Ts... ts){ return std::vector(ts...))>(a,make_v(ts...)); } #include template class modint { using u32 = std::uint_fast32_t; using u64 = std::uint_fast64_t; using i64 = std::int_fast64_t; inline u64 apply(i64 x) { return (x >= 0 ? x : x + Modulus); }; public: u64 a; static constexpr u64 mod = Modulus; constexpr modint(const u64 & x = 0) noexcept : a(x % Modulus) {} constexpr u64 &value() noexcept { return a; } constexpr const u64 &value() const noexcept { return a; } const modint inverse() const { return modint(1) / *this; } const modint pow(i64 k) const { return modint(*this) ^ k; } constexpr modint & operator+=(const modint & rhs) noexcept { a += rhs.a; if (a >= Modulus) a -= Modulus; return *this; } constexpr modint & operator-=(const modint & rhs) noexcept { if (a < rhs.a) a += Modulus; a -= rhs.a; return *this; } constexpr modint & operator*=(const modint & rhs) noexcept { a = a * rhs.a % Modulus; return *this; } constexpr modint & operator/=(modint rhs) noexcept { u64 exp = Modulus - 2; while (exp) { if (exp % 2) (*this) *= rhs; rhs *= rhs; exp /= 2; } return *this; } constexpr modint & operator^=(u64 k) noexcept { auto b = modint(1); while(k) { if(k & 1) b = b * (*this); (*this) *= (*this); k >>= 1; } return (*this) = b; } constexpr modint & operator=(const modint & rhs) noexcept { a = rhs.a; return (*this); } constexpr modint operator+(const modint & rhs) const noexcept { return modint(*this) += rhs; } constexpr modint operator-(const modint & rhs) const noexcept { return modint(*this) -= rhs; } constexpr modint operator*(const modint & rhs) const noexcept { return modint(*this) *= rhs; } constexpr modint operator/(const modint & rhs) const noexcept { return modint(*this) /= rhs; } constexpr modint operator^(const u64 & k) const noexcept { return modint(*this) ^= k; } constexpr modint operator-() const noexcept { return modint(Modulus - a); } constexpr modint operator++() noexcept { return (*this) = modint(*this) + 1; } constexpr modint operator--() noexcept { return (*this) = modint(*this) - 1; } const bool operator==(const modint & rhs) const noexcept { return a == rhs.a; }; const bool operator!=(const modint & rhs) const noexcept { return a != rhs.a; }; const bool operator<=(const modint & rhs) const noexcept { return a <= rhs.a; }; const bool operator>=(const modint & rhs) const noexcept { return a >= rhs.a; }; const bool operator<(const modint & rhs) const noexcept { return a < rhs.a; }; const bool operator>(const modint & rhs) const noexcept { return a > rhs.a; }; explicit operator bool() const { return a; } explicit operator u32() const { return a; } friend std::ostream & operator<<(std::ostream & os, const modint & p) { return os << p.a; } friend std::istream & operator>>(std::istream & is, modint & p) { u64 t; is >> t; p = modint(t); return is; } }; using mint = modint<(int)(1e9 + 7)>; int main() { int n, d, k; scanf("%d%d%d", &n, &d, &k); mint sum = 1; std::vector dp(k + 1, 0); dp[0] = 1; while(n--) { mint sum = 0; std::vector to(k + 1, 0); for(int i = 0; i < k; i++) { sum += dp[i]; if(i >= d) sum -= dp[i - d]; to[i + 1] = sum; } dp.swap(to); } printf("%llu\n", dp[k].value()); return 0; }