#include #ifdef _DEBUG #include "debug.hpp" #else #define debug(...) #endif #define REP(i, m, n) for(int i = (int)(m); i < (int)(n); ++i) #define rep(i, n) REP(i, 0, n) using namespace std; using ll = long long; using ld = long double; using pll = pair; template inline bool chmax(T &a, const U &b) { if(a < b) { a = b; return true; } return false; } template inline bool chmin(T &a, const U &b) { if(a > b) { a = b; return true; } return false; } constexpr int MOD = 1e9+7; //constexpr int MOD = 998244353; struct mint { long long x; mint(long long x = 0) noexcept : x((x%MOD + MOD) % MOD) {} // basis mint operator-() const { return mint(-x); } mint& operator+=(const mint a) noexcept { if((x += a.x) >= MOD) x -= MOD; return *this; } mint& operator-=(const mint a) noexcept { if((x += MOD-a.x) >= MOD) x -= MOD; return *this; } mint& operator*=(const mint a) noexcept { (x *= a.x) %= MOD; return *this; } mint operator+(const mint a) const noexcept { return mint(*this) += a; } mint operator-(const mint a) const noexcept { return mint(*this) -= a; } mint operator*(const mint a) const noexcept { return mint(*this) *= a; } mint mpow(long long t) const noexcept { if(!t) return 1; mint a = mpow(t>>1); a *= a; if(t&1) a *= *this; return a; } // for prime MOD mint inv() const noexcept { return mpow(MOD-2); } mint& operator/=(const mint a) noexcept { return *this *= a.inv(); } mint operator/(const mint a) const noexcept { return mint(*this) /= a; } // comparison bool operator==(const mint &a) const noexcept { return this->x == a.x; } bool operator!=(const mint &a) const noexcept { return this->x != a.x; } // I/O stream friend istream& operator>>(istream& is, mint& a) noexcept { return is >> a.x; } friend ostream& operator<<(ostream& os, const mint& a) noexcept { return os << a.x; } }; // additional mint mpow(const long long &a, long long n) noexcept { return mint(a).mpow(n); } mint mpow(const mint &a, long long n) noexcept { return a.mpow(n); } int n, d, k; mint dp[310][100000], sum[310][100000]; int main() { cin.tie(0); ios::sync_with_stdio(false); cin >> n >> d >> k; dp[0][0] = 1; rep(j, k) sum[0][j+1] += sum[0][j]+dp[0][j]; rep(i, n) rep(j, k) { dp[i+1][j+1] = sum[i][j+1]-sum[i][max(0, j-d+1)]; sum[i+1][j+2] += sum[i+1][j+1]+dp[i+1][j+1]; } cout << dp[n][k] << '\n'; return 0; }