30

#include <iostream>
using namespace std;
class MyCin
{
   bool value;
public:
   MyCin():value(true){ }
   operator bool(){return value;}
   MyCin& operator>>(int& n){
        cin >> n;
        if(n == -1)
            this -> value = false;
        return *this;
   }
};
int main()
{
    MyCin m;
    int n1,n2;
    while( m >> n1 >> n2) 
        cout  << n1 << " " << n2 << endl;
    return 0;
}