#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;

#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define rep(i,a,b) for (int i = (a); i < (b); ++i)

mt19937 rng(random_device{}());

int main()
{
    cin.tie(0)->sync_with_stdio(0);

    int x, y;
    cin >> x >> y;
    if (x == y) cout << 0 << endl;
    else if (y == 0) cout << 1 << endl;
    else if (x == 0) cout << 2 << endl;
    else if (x + y == 0) cout << 3 << endl;
    else cout << -1 << endl;
    
    return 0;
}