#include <iostream>
#include <cstdio>
using namespace std;
const int MOD = (int)1e9+7;
int dp[101][20001];

int main(void){
    int N, S, K; cin >> N >> S >> K;

    // (S-NK)のN分割を求めれば良い。
    int A = S - N * (N-1) * K / 2;
    if(A < 0){
        cout << "0\n";
        return 0;
    }

    dp[0][0] = 1;
    for(int i = 1; i <= N; i++){
        for(int j = 0; j <= A; j++){
            if(j >= i) dp[i][j] = (dp[i][j-i] + dp[i-1][j]) % MOD;
            else dp[i][j] = dp[i-1][j];
        }
    }

    cout << dp[N][A] << '\n';
    return 0;
}