main

#include <iostream>
#include <string>
using namespace std;

int main ()
{
  string command, city1, city2;
  while (cin >> command)
  {
    if(command != "insert" && "remove" && "print" && "distance" && "path")
      cout << "error\n";
    else
      cin >> city1 >> city2;
  }
}