#include "bits/stdc++.h"

using namespace std;
using ll = long long;
using ull = unsigned long long;

typedef pair<ll, ll> P;
typedef pair<ll, P> PP;

const ll MOD = 1e9 + 7;
const ll INF = 9e18;
const double eps = -1e10;
const int di[4] = { 1,0,-1,0 }, dj[4] = { 0,1,0,-1 };

#define ALL(x) (x).begin(),(x).end()
#define pb push_back
#define eb emplace_back
#define fr first
#define sc second

int n, s, k;
ll dp[110][20010];

int main() {
	cin >> n >> s >> k;
	for (int i = 1;i < n;i++) {
		s -= k * i;
	}
	if (s < 0) {
		cout << 0 << endl;
		return 0;
	}
	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];
		}
	}
	cout << dp[n][s] << endl;
	return 0;
}