#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cstring>
#include <queue>
#include <vector>
#include <functional>
#include <map>
#include <set>
#include <cmath>
#include <string>
#define SIZE 200005
#define INF 1000000005LL
#define MOD 1000000007

using namespace std;
typedef long long int ll;
typedef pair <int,int> P;

int dp[105][20005];

int N,S,K;

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