#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
using namespace std;
int main()
{
    int n,m;
    int t;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        t=(m%n)-1;
        if(t<0)
            t=n-1;
        printf("%d\n",t);
    }
    return 0;
}