#include using namespace std; using ll=int64_t; #define rep(i,n) for(int i=0;i<(n);++i) const ll MOD =1e9+7; int main(){ int N,S,K; cin>>N>>S>>K; vector> dp(N,vector(S+1)); dp[0][0] = 1; for(int i=0;i=0) dp[i][j] += dp[i][j-(N-i)]; if(i>0&&j-K*(N-i)>=0) dp[i][j] = (dp[i][j]+dp[i-1][j-K*(N-i)])%MOD; } } cout<