#include <bits/stdc++.h>
using namespace std;
using ll = long long;

#define rep(i,a,n) for (long long i = (a); i < (long long)(n); i++)
#define erep(i,a,n) for (long long i = (a); i <= (long long)(n); i++)
#define rrep(i,a,n) for (long long i = (a); i > (long long)(n); i--)
#define rerep(i,a,n) for (long long i = (a); i >= (long long)(n); i--)

ll N, S, K;
ll mod = 1e9+7;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> N >> S >> K;
    vector<vector<ll>> dp(109, vector<ll>(2e4+9));
    ll KK = 0; 
    rep(i, 1, N) {
        KK += K * i;
    }
    dp[0][0] = 1;
    erep(i, 1, N) {
        erep(j, 0, S-KK) {
            if(j >= i) dp[i][j] = dp[i-1][j] + dp[i][j-i];
            else dp[i][j] = dp[i-1][j];
            dp[i][j] %= mod;
        }
    }

    ll idx = max(0LL, S-KK);
    cout << dp[N][idx] << endl;
    
    return 0;
}