#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int A,B;
    cin >> A >> B;
    int ans;
    if(A == B)ans = 0;
    else if(B == 0)ans = 1;
    else if(A == 0)ans = 2;
    else ans = -1;
    cout << ans << endl;
}