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

using ll = long long;

using ld = long double;
using bl = bool;
//  using mint = modint;
//  mint::set_mod(m);

template <class T>
using pq = priority_queue<T, vector<T>>;
template <class T>
using pq_g = priority_queue<T, vector<T>, greater<T>>;

using pii = pair<int, int>;
using pll = pair<long long, long long>;

#define rep(i, n) for (ll i = 0; i < (n); ++i)
template <class T>
istream& operator>>(istream& i, vector<T>& v) {
    rep(j, size(v)) i >> v[j];
    return i;
}

const int inf = 1073741823;
const ll infl = 1LL << 60;

#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define drep(i, n) for (ll i = (n) - 1; i >= 0; --i)
#define nfor(i, s, n) for (ll i = s; i < n; i++)
#define dfor(i, s, n) for (ll i = (s) - 1; i >= n; i--)

#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()

#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)

#define Yes cout << "Yes" << endl
#define No cout << "No" << endl
#define YN                     \
    {                          \
        cout << "Yes" << endl; \
    }                          \
    else {                     \
        cout << "No" << endl;  \
    }  // if(a==b)YN;

#define vc_unique(v) v.erase(unique(v.begin(), v.end()), v.end());
#define vc_rotate(v) rotate(v.begin(), v.begin() + 1, v.end());

#define pop_cnt(s) ll(popcount(uint64_t(s)))

#define next_p(v) next_permutation(v.begin(), v.end())

vector<int> dx = {1, 0, -1, 0};  // vl dx={1,1,0,-1,-1,-1,0,1};
vector<int> dy = {0, 1, 0, -1};  // vl dy={0,1,1,1,0,-1,-1,-1};

bool out_grid(ll i, ll j, ll h, ll w = -1) {
    if (w == -1) {
        w = h;
    }
    return (!(0 <= i && i < h && 0 <= j && j < w));
}

#define vvl_rotate(v)                                   \
    {                                                   \
        ll n = size(v);                                 \
        vvl nx(n, vl(n));                               \
        rep(i, n) rep(j, n) nx[j][n - i - 1] = v[i][j]; \
        swap(nx, v);                                    \
    }  // 時計回りに90°回転
// #define vvl_rotate(v) {ll n = size(v);vvl
// nx(n,vl(n));rep(i,n)rep(j,n)nx[n-j-1][i]=v[i][j];swap(nx,v);}//反時計周りに90°回転

#define vs_rotate(v)                                    \
    {                                                   \
        ll n = size(v);                                 \
        vs nx(n, string(n, '.'));                       \
        rep(i, n) rep(j, n) nx[j][n - i - 1] = v[i][j]; \
        swap(nx, v);                                    \
    }  // 文字列版 時計回りに90°回転
// #define vs_rotate(v) {ll n = size(v);vs
// nx(n,string(n,'.'));rep(i,n)rep(j,n)nx[n-j-1][i]=v[i][j];swap(nx,v);}//文字列版　反時計周りに90°回転

#define vvl_transpos(v)                         \
    {                                           \
        ll n = size(v);                         \
        vvl nx(n, vl(n));                       \
        rep(i, n) rep(j, n) nx[j][i] = v[i][j]; \
        swap(nx, v);                            \
    }
#define vs_transpos(v)                          \
    {                                           \
        ll n = size(v);                         \
        vs nx(n, string(n, '.'));               \
        rep(i, n) rep(j, n) nx[j][i] = v[i][j]; \
        swap(nx, v);                            \
    }

#define euclid(x, y) ((x) * (x) + (y) * (y))  // ユークリッド距離 2乗のまま
#define manhattan(x1, x2, y1, y2) \
    (abs(x1 - x2) + abs(y1 - y2))  // マンハッタン距離 = |x1-x2|+|y1-y2|

ll nc2(ll x) { return x * (x - 1) / 2; }
ll nc3(ll x) { return x * (x - 1) * (x - 2) / 6; }

//----------------------------------------------

//-----------6.デバックや出力系------------------
void print(ld x) { printf("%.20Lf\n", x); }

#define print_vec(v)                   \
    {                                  \
        ll n = size(v);                \
        rep(i, n) cout << v[i] << " "; \
        cout << endl;                  \
    }  // 一次元配列を出力する(改行なし)

#define vc_cout(v)                      \
    {                                   \
        ll n = size(v);                 \
        rep(i, n) cout << v[i] << endl; \
    }  // 一次元配列を出力する(改行あり)
#define vv_cout(v)                                         \
    {                                                      \
        ll n = size(v);                                    \
        rep(i, n) {                                        \
            rep(j, size(v[i])) { cout << v[i][j] << ' '; } \
            cout << endl;                                  \
        }                                                  \
    }  // 二次元配列を出力する

//----------------------------------------------
ll mod = 1e9 + 7;
int main() {
    cout << fixed << setprecision(10);
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    ll n, s, k;
    cin >> n >> s >> k;

    s -= k * n * (n - 1) / 2;

    if (s < 0) {
        cout << 0 << endl;
        return 0;
    }

    vector dp(s + 1, vector<ll>(n + 1));
    dp[0][1] = 1;
    rep(i, s + 1) {
        rep(j, n + 1) {
            if (i - j >= 0) {
                dp[i][j] += dp[i - j][j];
            }
            if (j > 0) dp[i][j] += dp[i][j - 1];
            dp[i][j] %= mod;
        }
    }
    cout << dp[s][n] << endl;
    return 0;
}