#include <bits/stdc++.h>
#define REP(i,n) for(int i = 0; i < (int)(n); ++i)
typedef long long ll;
using namespace std;

ll gcd(ll a, ll b){
    if(b>0) return gcd(b,a%b);
    else return a;
}

int main(){
    ll N, D;
    cin >> N >> D;
    cout << N/gcd(N,D)-1 << endl;
    return 0;
}