#include <map>
#include <set>
#include <list>
#include <deque>
#include <queue>
#include <cmath>
#include <stack>
#include <string>
#include <vector>
#include <cctype>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <utility>
#include <iostream>
#include <iterator>
#include <algorithm>
using namespace std;
#define REP(i, n) for(int i = 0; i < n; ++i)
#define REP1(i, a, n) for(int i = a; i <= n; ++i)
#define REPD(i, n) for(int i = n; i >= 0; --i)
#define clm(m, a) memset(m, a, sizeof(m))
#define first fi;
#define second se;
typedef long long ll;
typedef pair<int, int> pii;
int n, m;

int main()
{
#ifdef LOCAL
//freopen("in","r",stdin);
#endif
    while(~scanf("%d%d", &n, &m)) {
        printf("%d\n", (m-1) % n);
    }
    return 0;
}