#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int main(){
	long long n,x,a,res;
	cin >> n >> x;
	a = max(n-x,x)
	if(n%x == 0)cout << a*3 <<endl;
	else cout << a*4 <<endl;
	return 0;
}