#include <cstdio>

int MOD = 1e9 + 7;
int dp[101][20001];

int main(){
    int N, S, K;
    scanf("%d %d %d", &N, &S, &K);

    dp[0][0] = 1;
    for(int i=1;i<=N;i++){
        for(int j=0;j<=S;j++){
            int idx = j-(N-i+1);
            dp[i][j] = (dp[i-1][j] + (idx >= 0 ? dp[i][idx] : 0)) % MOD;
        }
    }

    int p = S-K*N*(N-1)/2;
    if(p >= 0){
        printf("%d\n", dp[N][p]);
    }else{
        puts("0");
    }
}