#include<cstdlib>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<vector>
#include<string>
#include<map>

using namespace std;

int main()
{
    int a,b;
    while(cin>>a>>b)
        cout<<(b-1)%a<<endl;
    return 0;
}