#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

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

int main(){
    //*
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    /*/
      /*/

    ll N, D;
    std::cin >> N >> D;

    std::cout << N / gcd(N, D) - 1 << std::endl;
}