#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <numeric>
#include <cstring>
#include <cmath>
#include <set>
#include <queue>
#include <stack>

const int MOD = 1e9 + 7;
const int iINF = 1000000000;
const long long int llINF = 1000000000000000000;
#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;
using ll = long long int;
using P = pair<int, int>;
using edge = struct
{
    int to;
    int cost;
};

ll gcd(int a, int b)
{
    if (b > a)
        gcd(b, a);

    return b != 0 ? gcd(b, a % b) : a;
}

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