#include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <utility>
#include <queue>

#define inf  1000000007
#define ll long long
#define PA pair<int,int>
#define PPAP pair<int,pa>
#define  MP make_pair
#define  PB push_back

using namespace std;


ll dp[110][20500];

int main(){
	ll n,s,k;
	cin >> n >> s >> k;
	s -= (n-1)*k*n/2;
	if(s<0){
		cout << 0 << endl;
	}else{
		ll mod = inf;
		for(int i=1;i<=n;i++){
			dp[i][0]=1;
		}
		for(int i=1;i<=n;i++){
			for(int j=1;j<=s;j++){
				if(j-i>=0){
					dp[i][j]=(dp[i][j]+dp[i][j-i]+dp[i-1][j])%mod;	
				}else{
					dp[i][j]=(dp[i][j]+dp[i-1][j])%mod;	
				}
			}
		}
		cout << dp[n][s] << endl;
	}
	return 0;
}