#include <iostream>

using namespace std;

int main()
{
    string in;
    
    int counts[12] = {0};
	
    int result = 0;
    
    while(cin >> in) for(int i = 0; i < 12; i++) result = ((counts[i] += (in[i]=='1')?1:-1)>0)?(result|1<<(11-i)):(result&~(1<<(11-i)));
    
    cout << result*(result^0x0FFF) << endl;

    return 0;
}