#include <bits/stdc++.h>
using namespace std;
using LL = long long;

int main() {
    
    // 1. 入力情報取得.
    LL N, D;
    scanf("%llu %llu", &N, &D);
    
    // 2. 何回ぴょんできるかを計算.
    LL ans = 0;
    LL gcd = __gcd(N, D);
    N /= gcd, D /= gcd;
    if(N % D == 0) ans = N / D - 1;
    else           ans = N - 1;
    
    // 3. 出力.
    printf("%llu\n", ans);
    return 0;
    
}