// No.269 見栄っ張りの募金活動

// 分割数による解法

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
// const int INF = 2147483647;
// const ll INF = 9223372036854775807;

// modint: mod 計算を int を扱うように扱える構造体
template<int MOD> struct ModInt {
	long long val;
	constexpr ModInt(long long v = 0) noexcept : val(v % MOD) {
		if (val < 0) val += MOD;
	}
	constexpr int getmod() { return MOD; }
	constexpr ModInt operator - () const noexcept {
		return val ? MOD - val : 0;
	}
	constexpr ModInt operator + (const ModInt& r) const noexcept { return ModInt(*this) += r; }
	constexpr ModInt operator - (const ModInt& r) const noexcept { return ModInt(*this) -= r; }
	constexpr ModInt operator * (const ModInt& r) const noexcept { return ModInt(*this) *= r; }
	constexpr ModInt operator / (const ModInt& r) const noexcept { return ModInt(*this) /= r; }
	constexpr ModInt& operator += (const ModInt& r) noexcept {
		val += r.val;
		if (val >= MOD) val -= MOD;
		return *this;
	}
	constexpr ModInt& operator -= (const ModInt& r) noexcept {
		val -= r.val;
		if (val < 0) val += MOD;
		return *this;
	}
	constexpr ModInt& operator *= (const ModInt& r) noexcept {
		val = val * r.val % MOD;
		return *this;
	}
	constexpr ModInt& operator /= (const ModInt& r) noexcept {
		long long a = r.val, b = MOD, u = 1, v = 0;
		while (b) {
			long long t = a / b;
			a -= t * b; swap(a, b);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	constexpr bool operator == (const ModInt& r) const noexcept {
		return this->val == r.val;
	}
	constexpr bool operator != (const ModInt& r) const noexcept {
		return this->val != r.val;
	}
	friend constexpr ostream& operator << (ostream &os, const ModInt<MOD>& x) noexcept {
		return os << x.val;
	}
	friend constexpr ModInt<MOD> modpow(const ModInt<MOD> &a, long long n) noexcept {
		if (n == 0) return 1;
		auto t = modpow(a, n / 2);
		t = t * t;
		if (n & 1) t = t * a;
		return t;
	}
};

const int MOD = 1000000007;
using mint = ModInt<MOD>;

// 分割数
template<class T> struct Partition {
	vector<vector<T>> P;

	constexpr Partition(int N_MAX, int K_MAX) noexcept : P(N_MAX + 1, vector<T>(K_MAX + 1, 0)) {
		for (int k = 0; k <= K_MAX; k++) P[0][k] = 1;
		for (int n = 1; n <= N_MAX; n++) {
			for (int k = 1; k <= K_MAX; k++) {
				P[n][k] = P[n][k-1] + (n-k >= 0 ? P[n-k][k] : 0);
			}
		}
	}

	constexpr T get(int n, int k) {
		if (n < 0 || k < 0) return 0;
		return P[n][k];
	}
};

int main() {
	int N, S, K;
	cin >> N >> S >> K;

	ll fixed = 0;
	for (int i=1; i<N; i++) {
		fixed += K * i;
	}

	//cout << "fixed = " << fixed << endl; // **** debug ****

	if (fixed > S) {
		cout << 0 << endl;
		return 0;
	}

	Partition<mint> pt(S - fixed, N);

	mint ans = pt.get(S - fixed, N);

	cout << ans << endl;

	return 0;
}