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

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const int MOD = 1e9 + 7;

int dp[110][20010] = {};

int main(){
    int n, s, k;
    cin >> n >> s >> k;

    dp[0][0] = 1;
    for (int i = 1; i <= n; ++i) {
        for (int j = 0; j < s; ++j) {
            if(j - i >= 0) dp[i][j] = (dp[i][j-i] + dp[i-1][j]) % MOD;
            else dp[i][j] = dp[i-1][j];
        }
    }

    for (int i = 0; i < n; ++i) {
        s -= i * k;
    }

    cout << dp[n][s] << endl;
}