#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const double pi=3.141592653589793;
typedef unsigned long long ull;
typedef long double ldouble;
const ll INF=1e18;
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }


int main(){
    int N, S, K, mod = 1e9+7;
    cin >> N >> S >> K;
    if(N * (N-1) / 2 * K > S) {
        cout << 0 << endl;
        return 0;
    }
    int M = N;
    N = S - K * (N-1) * N / 2;
    vector<vector<int> > dp(M+1, vector<int>(N+1));
    dp[0][0] = 1;
    rep2(i, 1, M+1){
        rep(j, N+1){
            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[M][N] << endl;
}