# include <iostream>
using namespace std;
int main ()
{
int n,k,sol;
    cin>>n>>k;
        if(int(n/2) && 1<=k<=n<=50){
        if(k<=n/2) sol=n-3;
        if(k>n/2) sol=k-3;
        if(n==2) sol=0;
        }
    cout<<sol<<endl;
}

Edited by author 26.06.2014 22:00

AC

if(k<=n/2) sol=n-2-k;

Edited by author 09.07.2014 22:52