#include <bits/stdc++.h>
#include <set>
#include <cstdio>
#include <vector>
#include <iostream>
#include <utility>

#define fir first
#define sec second
#define get(n) scanf("%d",&n);
#define gets(s) string s;cin >> (s);
#define All(s) (c).begin(), (c).end()
#define chmin(x, y) x = min(x, y);
#define chmax(x, y) x = max(x, y);
#define rep(i, j) for (int (i)=0;(i)<(j);(i)++)
#define repk(i, j, k) for(int (i)=(j);(i)<(k);(i)++)
#define dump(x)  cout << #x << " = " << (x) << endl;
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
using namespace std;
typedef long long int ll;
const ll INF = 10241024;
const int MOD = 1e9 + 7;
int N,S,K;

void input(){
    cin >> N >> S >> K;
}

void solve(){
    input();
    int s = S - K*N*(N-1)/2;
    vector<int> v(s+1);
    v[0] = 1;
    rep(i,N-1){
        for(int j=N;i>0;j++){
            v[i+j] += v[i];
        }
    }

    int ans = v[s] % MOD; 
    cout << ans << endl;
    
}

int main () {
    solve();
    return 0;
}