traffic light

#include <iostream>
#include <string>
using namespace std;
int main() {
string a, b, c;
  cin >> a >> b >> c;
  if (a == "black" && b == "black" && c == "green") {
    cout << "black" << endl << "black" << endl << "GREEN";
  } else if(a == "black" && b == "black" && c == "GREEN") {
    cout << "black" << endl << "yellow" << endl << "black";
  } else if(a == "black" && b == "yellow" && c == "black") {
    cout << "red" << endl << "black" << endl << "black";
  } else if(a == "red" && b == "black" && c == "black") {
    cout << "red" << endl << "yellow" << endl << "black";
  } else if(a == "red" && b == "yellow" && c == "black") {
    cout << "black" << endl << "black" << endl << "green";
  }  else if(a == "black" && b == "YELLOW" && c == "black") {
      cout << "black" << endl << "YELLOW" << endl << "black";
    } else {
      cout << "error";
    }

}