#include<cstdio>
#include<cmath>
#include<algorithm>

static const int MAX_N = 100;
static const int MAX_S = 20000;
static const int M = pow(10, 9) + 7;

int N, S, K;

int dp[MAX_N + 1][MAX_S + 1];

int main(){
    scanf("%d %d %d", &N, &S, &K);
    S -= K * ((N - 1) * N / 2);
    if(S >= 0){
        dp[0][0] = 1;
        for(int i = 1; i <= N; i++){
            for(int j = 0; j <= S; j++){
                if(j - i >= 0) dp[i][j] = (dp[i][j - i] + dp[i - 1][j]) % M;
                else dp[i][j] = dp[i - 1][j];
            }
        }
        printf("%d\n", dp[N][S]);
    }else{
        printf("%d\n", 0);
    }
}