#include <iostream>
#include <string>

using namespace std;

char consensus (char a, char b, char c){
  return (a == b && b == c && c != '.') ? c : 0;
}

bool Valid (const string &s){

  int numXs = 0, numOs = 0;
  for (int i = 0; i < s.length(); i++){
    if (s[i] == 'X') numXs++;
    if (s[i] == 'O') numOs++;
  }

  char r1 = consensus (s[0], s[1], s[2]);
  char r2 = consensus (s[3], s[4], s[5]);
  char r3 = consensus (s[6], s[7], s[8]);
  char c1 = consensus (s[0], s[3], s[6]);
  char c2 = consensus (s[1], s[4], s[7]);
  char c3 = consensus (s[2], s[5], s[8]);
  char d1 = consensus (s[0], s[4], s[8]);
  char d2 = consensus (s[2], s[4], s[6]);

  // no two parallel row/columns can have three-in-a-row

  if (r1 && r2 || r1 && r3 || r2 && r3) return false;
  if (c1 && c2 || c1 && c3 || c2 && c3) return false;

  // draw is possible only if X makes 5 marks and O makes 4 marks

  if (!(r1 || r2 || r3 || c1 || c2 || c3 || d1 || d2) && 
      (numXs != 5 || numOs != 4)) return false;

  // if O wins, then both make the same number of marks
  
  if ((r1=='O' || r2=='O' || r3=='O' || c1=='O' || c2=='O' || c3=='O' || d1=='O' || d2=='O') && 
      numXs != numOs) return false;

  // if X wins, then X has one more mark than O

  if ((r1=='X' || r2=='X' || r3=='X' || c1=='X' || c2=='X' || c3=='X' || d1=='X' || d2=='X') && 
      numXs != numOs + 1) return false;
  
  return true;
}

int main(){
  while (true){
    string s;
    getline (cin, s);
    if (s == "end") break;
    cout << (Valid (s) ? "valid" : "invalid") << endl;
  }  
}