#include<iostream>

using namespace std;

int main() {
   int i;

   do {

       cin >> i;

        // If cin succeeded in reading in an int value.
       if(!cin.fail())
           cout << i << endl;

       // cin failed, remove the invalid values, and
       // clear the error flag.
       else {
           cin.clear();
           cin.ignore(numeric_limits<streamsize>::max(),'\n');
           cout << "Invalid value!" << endl;
       }
   }while (i!=-1);
}