#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vvvvll = vector<vvvll>;
using vvvvvll = vector<vvvvll>;
using vvvvvvll = vector<vvvvvll>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvvb = vector<vvb>;
using vvvvb = vector<vvvb>;
using vd = vector<double>;
using vvd = vector<vd>;
using vvvd = vector<vvd>;
using vvvvd = vector<vvvd>;
using vvvvvd = vector<vvvvd>;
#define all(A) A.begin(),A.end()
#define ALL(A) A.begin(),A.end()
#define rep(i, n) for (ll i = 0; i < (ll) (n); i++)
using pqr = priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>>;
#define tN(t) (t==1?XN:YN)
#define tS(t) (t==1?XS:YS)
#define tA(t) (t==1?XA:YA)

template<class T>
bool chmax(T& p, T q, bool C = 1) {
    if (C == 0 && p == q) {
        return 1;
    }
    if (p < q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

template<class T>
bool chmin(T& p, T q, bool C = 1) {
    if (C == 0 && p == q) {
        return 1;
    }
    if (p > q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

ll gcd(ll(a), ll(b)) {
    if (b == 0)return a;
    ll c = a;
    while (a % b != 0) {
        c = a % b;
        a = b;
        b = c;
    }
    return b;
}
ll sqrtz(ll N) {
    ll L = 0;
    ll R = sqrt(N) + 10000;
    while (abs(R - L) > 1) {
        ll mid = (R + L) / 2;
        if (mid * mid <= N)L = mid;
        else R = mid;
    }
    return L;

}

vector<ll> fact, factinv, inv;
const ll mod = 1e9 + 7;
void prenCkModp(ll n) {
    fact.resize(n + 5);
    factinv.resize(n + 5);
    inv.resize(n + 5);
    fact[1] = fact[1] = 1;
    factinv[1] = factinv[1] = 1;
    inv[1] = 1;
    for (ll i = 2; i < n + 5; i++) {
        fact[i] = (fact[i - 1] * i) % mod;
        inv[i] = mod - (inv[mod % i] * (mod / i)) % mod;
        factinv[i] = (factinv[i - 1] * inv[i]) % mod;
    }

}

ll nCk(ll n, ll k) {
    if (n < k) return 0;
    return fact[n] * (factinv[k] * factinv[n - k] % mod) % mod;
}

//const ll mod=1e9+7;
ll N, S, K;
vvll DP;

ll dfs(ll n, ll s) {
    if (DP[n][s] >= 0)return DP[n][s];
    if (n == 0) {
        return (s == 0);
    }
    else {
        ll res = 0;
        res+=dfs(n-1,s);
        if(s>=n)res+=dfs(n,s-n);
        res%=mod;
        DP[n][s] = res;
        return res;

    }
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    cin >> N >> S >> K;
    DP.assign(N + 1, vll(S + 1, -1));
    S -= ((N * (N - 1)) / 2) * K;
    if (S < 0) {
        cout << 0 << endl;
        return 0;
    }
    cout << dfs(N, S) << endl;
}