#include <bits/stdc++.h>
using namespace std;

using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;
using LL = long long;
using VL = vector<LL>;
using VVL = vector<VL>;
using PLL = pair<LL, LL>;
using VS = vector<string>;

#define ALL(a)  begin((a)),end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
#define SORT(c) sort(ALL((c)))
#define RSORT(c) sort(RALL((c)))
#define UNIQ(c) (c).erase(unique(ALL((c))), end((c)))

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

#define FF first
#define SS second

#define DUMP(x) cout<<#x<<":"<<(x)<<endl
template<class S, class T>
istream& operator>>(istream& is, pair<S,T>& p){
  return is >> p.FF >> p.SS;
}
template<class T>
istream& operator>>(istream& is, vector<T>& xs){
  for(auto& x: xs)
	is >> x;
  return is;
}
template<class S, class T>
ostream& operator<<(ostream& os, const pair<S,T>& p){
  return os << p.FF << " " << p.SS;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T>& xs){
  for(unsigned int i=0;i<xs.size();++i)
	os << (i?" ":"") << xs[i];
  return os;
}
template<class T>
void maxi(T& x, T y){
  if(x < y) x = y;
}
template<class T>
void mini(T& x, T y){
  if(x > y) x = y;
}


const double EPS = 1e-10;
const double PI  = acos(-1.0);
const LL MOD = 1e9+7;

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  int X, Y;
  cin >> X >> Y;
  map<PLL,int> ds;
  ds[MP(X,Y)] = 0;
  queue<PLL> q;
  q.push(MP(X,Y));
  int ans = -1;
  while(!q.empty()){
	PLL p = q.front();
	q.pop();
	int t = ds[p];
	if(p.FF == p.SS){
	  ans = t;
	  break;
	}
	
	if(!ds.count(MP(p.SS,p.FF))){
	  ds[MP(p.SS,p.FF)] = t+1;
	  q.push(MP(p.SS,p.FF));
	}
	if(!ds.count(MP(p.FF+p.SS,p.FF-p.SS))){
	  ds[MP(p.FF+p.SS,p.FF-p.SS)] = t+1;
	  q.push(MP(p.FF+p.SS,p.FF-p.SS));
	}
  }

  cout << (ans>100?-1:ans) << endl;

  return 0;
}