while(cin>>n1>>n2)

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