#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define each(a, b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define pb push_back
#define show(x) cout <<#x<<" = "<<(x)<<endl
#define spair(p) cout <<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout <<" "<<kbrni;cout<<endl

using namespace std;

typedef pair<int,int>P;

const int MAX_N = 101;
const int MAX_V = 21000;

ll dp[MAX_N][MAX_V];

int main()
{
    int n,s,K;
    cin >> n >> s >> K;
    int rem = s - K*n*(n-1) / 2;
    int nw = 0;
    if(rem < 0){
        cout << "0\n";
    }else{
        dp[0][0] = 1;
        rep(i,n){
            rep(j,rem+1){
                if(j >= i+1){
                    dp[i+1][j] = (dp[i+1][j] + dp[i+1][j-i-1]) % MOD;
                }
                dp[i+1][j] = (dp[i+1][j] + dp[i][j]) % MOD;
            }
        }
        cout << dp[n][rem] << endl;
    }
    return 0;
}