#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream>
#include<map>
#include <iomanip>
#include <time.h>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <cassert>
#include<fstream>
#include <cstdlib>
using namespace std;
#define Ma_PI 3.141592653589793
#define eps 0.00000001
#define LONG_INF 3000000000000000000
#define GOLD 1.61803398874989484820458
#define MAX_MOD 1000000007
#define REP(i,n) for(long long i = 0;i < n;++i)
#define seg_size 524288
map<pair<long long,long long>, int> wow;
int main() {
#define int long long
	int x, y;
	cin >> x >> y;
	if (x == y) {
		cout << "0" << endl;
		return 0;
	}
	queue<pair<int, int>> next;
	next.push(make_pair(x, y));
	wow[make_pair(x, y)] = 1;
	int cnt = 0;
	while (cnt < 100) {
		pair<int, int> now = next.front();
		next.pop();
		cnt++;
		if (wow[make_pair(now.second, now.first)] == 0) {
			wow[make_pair(now.second, now.first)] = wow[now]+1;
			next.push(make_pair(now.second, now.first));
		}
		if (wow[make_pair(now.first + now.second, now.first - now.second)] == 0) {
			wow[make_pair(now.first + now.second, now.first - now.second)] = wow[now] + 1;
			next.push(make_pair(now.first + now.second, now.first - now.second));
			if (now.first + now.second == now.first - now.second) {
				cout << wow[now] << endl;
				return 0;
			}
		}
	}
	cout << -1 << endl;
	return 0;
}