#include<bits/stdc++.h>
using namespace std;
int dp[20010][20010];
long long mod=1e9+7;
int main(){
	int n,s,k;
	cin>>n>>s>>k;
	int i=1;
	while(i*n<=s){
		i++;
		dp[1][i*n]=1;
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=s;j++){
			if(j-(n-i+1)<=s){
				dp[i][j]+=dp[i-1][j-k*(n-i+1)]%mod;
			}
			if(j-k*(n-i+1)<=s){
				dp[i][j]+=dp[i][j-(n-i+1)]%mod;
			}
		}
	}
	cout<<dp[n][s];
	return 0;
}