//活动地址: 牛客春招刷题训练营 - 编程打卡活动
#include<bits/stdc++.h>

using  namespace std;

#define mod 1000000007

typedef long long ll;

#define int  long long

inline ll read() // void int &n

{

    ll s=0,f=1;

    char c=getchar();

    while(c>'9'||c<'0')     

{

        if(c=='-')  

            f=-1;   

        c=getchar();

    }

    while(c>='0'&&c<='9')

    {

        s=(s<<1)+(s<<3)+c-'0';

        c=getchar();

    }

    return s*f;

}

inline void write(int n)

{

if(n<0)

{

  putchar('-');

  n=-n;

}

    

if(n>10) write(n/10);

putchar(n%10+'0');

}

int jiechen(int n)

{

    int sum = 1;

    for (int i = 2; i <= n; i++)

        sum = sum * i % mod;

    return sum % mod;

}

int qsm(ll a, ll p)

{

    ll s=1;

    while(p)

    {

        if(p&1)

         s=s*a%mod;

      a=a*a%mod;

    }

       return s;

}

ll isprime(ll x)

{

    if(x<2)

        return 0;

    for(int i=2;i<=x/i;i++)

        if(x%i==0)

            return 0;

    return 1;
}

bool cmp(int x, int y){
    return x>y;
}

const int N=3e6+10;

const int M =100000;


void solve(){
    // 这题主要看你能不能一下就想到那几种特殊情况 分四种情况  此外 误解
    int x,y;
    cin>>x>>y;
    if(x==y)cout<<0;
    else if(x==0)cout<<2;
    else if(y==0)cout<<1;
    else if(x+y==0)cout<<3;
    else cout<<-1;
}

signed main()

{

ios::sync_with_stdio(false);

cin.tie(0);

cout.tie(0);

    int _=1;

    //cin>>_;

    while(_--)

    {

        solve();

    }

    return 0;

}