#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < n; i++)
#define repp(i, n) rep(i, 0, n)
#define repb(i, a, b) for(int i = a; i >= b; i--)
#define all(a) a.begin(), a.end()
#define int long long
using namespace std;
typedef pair<int, int> P;

int gcd(int a, int b){
    if(a < b) swap(a, b);
    if(b == 0) return a;
    return gcd(b, a % b);
}

signed main(){
	int n, d;
    cin >> n >> d;
    cout << n / gcd(n, d) - 1 << endl;
}