#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<queue>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<string>
#include<cmath>
#include<cctype>
#include<ctime>
#include<bitset>
using namespace std;
const int maxlongint=2147483647;
const int inf=1000000000;
int main()
{
    int n,m;
    while(scanf("%d%d",&n,&m)==2)
    {
        cout<<(m-1)%n<<endl;
    }
}