#include <iostream>

#define all(c) c.begin(), c.end()
#define rall(c) c.rbegin(), c.rend()

using namespace std;

using ll =  long long;

constexpr ll MOD = 1000000007;
constexpr int N_MAX = 20000;
constexpr int M_MAX = 100;

namespace Partition {
    int n, m; // ボールの個数，グループ数
    ll p[N_MAX+1][M_MAX+1];
    
    void init(int nn, int mm) {
        n = nn;
        m = mm;
        p[0][0] = 1;
        for(int j=1;j<=m;++j) p[0][j] = 1;
        for(int i=1;i<=n;++i) {
            for(int j=1;j<=m;++j) {
                p[i][j] = (p[i][j-1] + (i-j<0?0:p[i-j][j])) % MOD;
            }
        }
    }

    const ll get(int i, int j) {
        return p[i][j];
    }
}

int main() {
    ll n,s,m;
    cin >> n >> s >> m;
    ll ss = s-n*(n-1)/2*m;

    if(ss < 0) {
        cout << 0 << endl;
        return 0;
    }

    Partition::init(ss, n);

    cout << Partition::get(ss, n) << endl;
}