#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll dp[100][20000];
int N, S, K;
ll M = pow(10,9) + 7;
int main(){
    cin >> N >> S >> K;
    if(K*N*(N-1)/2 > S){
        cout << 0 << endl;
        return 0;
    }
    int i, j;
    dp[0][0] = 1;
    if(K == 0){
        for(i=1; i<=N; i++){
            for(j=0; j<=S; j++){
                if(j-i < 0){
                    dp[i][j] = dp[i-1][j] % M;
                }
                else{
                    dp[i][j] = (dp[i][j-i] + dp[i-1][j]) % M;
                }
            }
        }
    }
    else if(K >= 1){
        for(i=1; i<=N; i++){
            int min_money = K*i*(i-1)/2;
            for(j=min_money; j<=S; j++){
                if(j < i-1){
                    dp[i][j] = 0;
                }
                else if(i-1 <= j && j < i){
                    dp[i][j] = dp[i-1][j-(i-1)] % M;
                }
                else{
                    dp[i][j] = (dp[i][j-i] + dp[i-1][j-(i-1)]) % M;
                }
            }
        }
    }
    cout << dp[N][S] << endl;
}