#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<(n);i++)
using ll = long long;
const ll INF = 1e9;
const ll mod=1000000007;

int main(){
    ll n, s, k;
    cin >> n >> s >> k;
    int ss = s - n * (n-1) * k / 2;
    if(ss<0){
        cout << 0 << endl;
        return 0;
    }
    ll dp[n+1][ss+1];//dp[i][j] := jのi分割の総数
    rep(i,n+1)rep(j,ss+1) dp[i][j] = 0;
    dp[0][0] = 1;
    for(int i=1; i<=n; i++){
        for(int j=0; j<=ss; 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];
            }
        }
    }
    cout << dp[n][ss] << endl;
}