#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i=0; i<(n);++i)
using ll = long long;

int main(){
    double X,Y,Z,ans;
    double price_per_gram;
    cin >> X >> Y >> Z;
    ans = 1000001.0;
    price_per_gram = (double) (Y/X);
    while (1){
        if((double)(ans/Z)>=price_per_gram){
            ans-=1.0;
        }
        else{
            break;
        }
    }
    cout << ans << endl;
}
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,s,t) for(int i = (int)(s); i < (int)(t); i++)
using p = pair<int,int>;

ll func(int n, int k){
    return max(0, min(k - 1, 2*n + 1 - k));
}

int main(){
    int n,k;
    cin >> n >> k;
    ll ans = 0;
    rep(i,2,2*n+1){
        ans += func(n, k + i) * func(n, i);
    }
    cout << ans << endl;
}