#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;
int main(){
  int N,D;
  cin >> N >> D;
  int i=1,ans=0;
  while(1){
    i+=D;
    i%=N;
    if(i==1)break;
    ans++;
  }
  cout << ans;
  return 0;
}