#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)s; i < (int)e; ++i)
#define all(a) (a).begin(), (a).end()

int main() {
    cin.tie(nullptr);
    
    ll N, D;
    cin >> N >> D;
    
    ll g = gcd(N, D);
    
    cout << N / g - 1<< '\n';
}