#include <bits/stdc++.h>
#include<iostream>
#include<iomanip>
#include<string>
#include<algorithm>
#include<vector>
#include<set>
#include<list>
#include<queue>
#include<math.h>
#include<bitset>
using ll = long long;
using namespace std;

int main()
{
    ll n, d, mod = -1, frac = 1;
    cin >> n >> d;
    if (n > 0 && d > 0) frac = gcd(n, d);
    if (n == d) cout << 0 << endl;
    else cout << n/frac -1 << endl;
}