#include<bits/stdc++.h>
//#include <atcoder/all>
#define rep(i, n) for(int i = 0; i < (n); ++i)
#define DEBUG
#ifdef DEBUG
#define DEBUG_PRINT(fm, ...) do{std::printf("%s:%d(%s)", __FILE__, __LINE__, __func__);std::cout << "DEBUG PRINT ";std::printf(fm, __VA_ARGS__);}while(0)
#define DEBUG_VAL(a, b) do{std::printf("%s:%d(%s)", __FILE__, __LINE__, __func__);std::cout <<"DEBUG VAL " << a << ":" << b << endl;}while(0)
#else
#define DEBUG_PRINT(...)do{}while(0);
#define DEBUG_VAL(a, b)do{}while(0);
#endif

using namespace std;
//using namespace atcoder;
using ll = long long;
using v1 = vector<int>;
using vl = vector<long long>;
using v2 = vector<vector<int>>;
using v3 = vector<vector<char>>;

int main(){
    int n, s, k;
    cin >> n >> s >> k;
    s -= n*k*(n-1)/2;
    int m=1e9+7;
    if(s < 0){
        cout << 0 << endl;
    }else{
        v2 dp(n+1, v1(s+1, 0));
        dp[0][0] = 1;
        for(int i = 1; i<=n; i++){
            for(int j = 0; j <= s; j++){
                if(j >= i) dp[i][j] = (dp[i][j-i] + dp[i-1][j])%m;
                else dp[i][j] = dp[i-1][j];
            }
        }
        cout << dp[n][s] << endl;
    }
}