#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
//using mint = modint998244353;
using mint = modint1000000007;
typedef long long ll;
typedef unsigned long long ull;
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int MAX = 1e9;
const int MIN = -1*1e9;
const ll MAXLL = 1e18;
const ll MINLL = -1*1e18;
//const ll MOD = 998244353;
//const ll MOD = 1000000007;

vector<vector<mint>> Partition(int N)
{
    vector<vector<mint>> DP(N+1,vector<mint>(N+1));
    for(int i = 0; i <= N; i++) DP[0][i] = 1;
    for(int i = 1; i <= N; i++)
    {
        for(int j = 1; j <= N; j++)
        {
            if(i < j) DP[i][j] = DP[i][j-1];
            else DP[i][j] = DP[i][j-1] + DP[i-j][j];
        }   
    }
    return DP;
}

int main()
{
    ll N,S,K; cin >> N >> S >> K;
    ll Cost = (1+(N-1))*(N-1)/2*K;
    vector<vector<mint>> DP = Partition(5010);
    if(S < Cost)
    {
        cout << 0 << endl;
        return 0;
    }

    cout << DP[S-Cost][N].val() << endl;
    return 0;
}