C++ :

#include<cstdio>
#include<cstring>
#include<cmath>
#include<iostream>
#include<algorithm>
using namespace std;

long long gcd(long long a,long long b)
{
    if(b==0)
        return a;
    else
        return gcd(b,a%b);
}

int main()
{
    //freopen( "B.txt", "r", stdin );
    //  freopen( "_B.txt", "w", stdout );
    long long  a,b;
    while(cin>>a>>b)
    {
        long long g=gcd(a,b);
        a=a/g;
        b=b/g;
//        cout<<a<<" "<<b<<endl;
        long long ans=a+b;
        long long sum=ans;
//        cout<<ans<<endl;
        bool flag=0;
        for(; ;)
        {
            if(ans&1)
            {
                if(ans==1)
                {
                    flag=1;
                }
                break;
            }
            ans/=2;
        }
        if(flag==0)
        {
            cout<<-1<<endl;
        }
        else
        {
            long long co=0;
            while(sum)
            {
                co++;
                sum/=2;
            }
            cout<<co-1<<endl;
        }
    }
    return 0;
}