#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) { return (ull)rng() % B; }

template <int mod> struct static_modint {
    using mint = static_modint;
    int x;

    static_modint() : x(0) {}
    static_modint(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    mint &operator+=(const mint &rhs) {
        if ((x += rhs.x) >= mod) x -= mod;
        return *this;
    }
    mint &operator-=(const mint &rhs) {
        if ((x += mod - rhs.x) >= mod) x -= mod;
        return *this;
    }
    mint &operator*=(const mint &rhs) {
        x = (int)(1LL * x * rhs.x % mod);
        return *this;
    }
    mint &operator/=(const mint &rhs) { return *this = *this * rhs.inv(); }

    mint pow(long long n) const {
        mint _x = *this, r = 1;
        while (n) {
            if (n & 1) r *= _x;
            _x *= _x;
            n >>= 1;
        }
        return r;
    }
    mint inv() const { return pow(mod - 2); }

    mint operator+() const { return *this; }
    mint operator-() const { return mint() - *this; }
    friend mint operator+(const mint &lhs, const mint &rhs) { return mint(lhs) += rhs; }
    friend mint operator-(const mint &lhs, const mint &rhs) { return mint(lhs) -= rhs; }
    friend mint operator*(const mint &lhs, const mint &rhs) { return mint(lhs) *= rhs; }
    friend mint operator/(const mint &lhs, const mint &rhs) { return mint(lhs) /= rhs; }
    friend bool operator==(const mint &lhs, const mint &rhs) { return lhs.x == rhs.x; }
    friend bool operator!=(const mint &lhs, const mint &rhs) { return lhs.x != rhs.x; }

    friend ostream &operator<<(ostream &os, const mint &p) { return os << p.x; }
    friend istream &operator>>(istream &is, mint &a) {
        int64_t t;
        is >> t;
        a = static_modint<mod>(t);
        return (is);
    }
};

const unsigned int mod = 1e9 + 7;
using modint = static_modint<mod>;
modint mod_pow(ll n, ll x) { return modint(n).pow(x); }
modint mod_pow(modint n, ll x) { return n.pow(x); }

template <typename T> struct Comination {
    vector<T> p, invp;

    Comination(int sz) : p(sz + 1), invp(sz + 1) {
        p[0] = 1;
        for (int i = 1; i <= sz; ++i) {
            p[i] = p[i - 1] * i;
        }
        invp[sz] = p[sz].inv();
        for (int i = sz - 1; i >= 0; --i) {
            invp[i] = invp[i + 1] * (i + 1);
        }
    }

    T comb(int n, int r) {
        if (r < 0 or n < r) return 0;
        return p[n] * invp[n - r] * invp[r];
    }
    T big_comb(T n, int r) {
        T res = invp[r];
        for (int i = 0; i < r; ++i) {
            res *= (n - i);
        }
        return res;
    }
};
using Comb = Comination<modint>;
Comb comb(1 << 20);

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, s, k;
    cin >> n >> s >> k;
    for (int i = 0; i < n; ++i) {
        s -= k * i;
    }
    if (s < 0) {
        cout << 0 << endl;
    } else {
        vector<modint> dp(s + 1);
        dp[0] = 1;
        for (int i = n; i >= 1; --i) {
            for (int j = i; j <= s; ++j) {
                dp[j] += dp[j - i];
            }
        }
        cout << dp[s] << endl;
    }
}