#include <iostream>

using namespace std;
typedef long long ll;
ll mod = 1000000007,dp[110][20010] = {}; // num/sum like partition dp
int main(){
    int i,j,n,s,k; cin >> n >> s >> k;
    dp[0][0] = 1;
    for(i=1;i<=n;i++){
        for(j=0;j<=s;j++){
            if(j>=i) (dp[i][j] += dp[i][j - i]) %= mod; //0 nasi
            if(j>=k*(i - 1)) (dp[i][j] += dp[i - 1][j - k*(i - 1)]) %= mod; //0 ari
        }
    }
    cout << dp[n][s] << endl;
}