#include <iostream>
#include <cctype>

using namespace std;

int main(void) {
  int i;

  do {
    cout << "Enter a number: ";
    //skip all non-integer characters
    while(!isdigit(cin.peek()) && cin.peek() != '-')
      cin.get();
    
    cin >> i;
    cout << i << endl;
  } while(i!=-1);
}