#include <cstdio>
#include <cstring>
#include <cmath>
#include <cassert>
#include <random>
#include <vector>
#include <algorithm>
#include <array>
#include <functional>
#include <utility>
#include <regex>
#include <tuple>
#include <map>

using namespace std;

int main(){
	int n,d;
	-scanf("%d%d",&n,&d);
	vector<bool> a(n,true);
	int c=0,p=0;
	while(a[(p+d)%n]){
		//printf("%d to %d %d\n",p,(p+d)%n,c);
		a[p]=false;
		p+=d;
		p%=n;
		c++;
	}
	printf("%d\n",c);
	return 0;
}