#include <iostream>
#include <iomanip>
#include <cmath>
#include <string>

using namespace std;

int main()
{

    char input;
    cout << "Zadej cislo ve dvojkove soustave:" << endl;

        while (cin.get(input)){
            if (input=='/n'){ cout << "Nespravny vstup." << endl;
             break;}
            if (input!=1 || input!=0) { cout << "Nespravny vstup." << endl;
            break;
            }
            else cout << "b" << endl;

}


    return 0;
}