#include <iostream>
#include <tuple>
#include <sstream>
#include <vector>
#include <cmath>
#include <ctime>
#include <cassert>
#include <cstdio>
#include <queue>
#include <set>
#include <map>
#include <fstream>
#include <cstdlib>
#include <string>
#include <cstring>
#include <algorithm>
#include <numeric>
using namespace std;
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define range(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define _GLIBCXX_DEBUG
typedef long long ll;
typedef double db;
typedef string str;
// head

int main(){
    int n,s,k;
    cin >> n >> s >> k;
    ll dp[101][20000];
    int maxs = s-k*(k-1)/2*n;
    range(i,1,n+1){
        range(j,maxs+1){
            if (j-i>=0){
                dp[i][j]=dp[i-1][j];
            }
            else{
                dp[i][j]=dp[i-1][j]+dp[i][j-i];
            }

        }
    }
    cout << dp[n][maxs];
}