#include<bits/stdc++.h>
#define EM 1000000
using namespace std;
using LL = long long;
using P = pair<LL, LL>;
LL LINF = 1e18;
int INF = 1e9;
LL mod = 1e9+7;
using vint = vector<int>;
using vLL = vector<LL>;
using vvint = vector<vector<int>>;
using vvLL = vector<vector<LL>>;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }


vector<vector<LL>>  dp(20010, vector<LL>(110, 0));

int main(){
    int N, S, K;
    cin >> N >> S >> K;
    S -= N*(N-1)/2*K;
    if(S < 0){
        cout << 0 << endl;
        return 0;
    }
    for(int i = 0;i < 20010;i++) dp[i][1] = 1;
    for(int n = 2;n < 110;n++){
        for(int s = 0;s < 20010;s++){
            dp[s][n] += dp[s][n-1];
            if(s-n >= 0)    dp[s][n] += dp[s-n][n];
            dp[s][n] %= mod;
        }
    }
    cout << dp[S][N] << endl;
}