// Arup Guha
// 1/27/2018
// Solution to 2017 MCPC Problem A: Nine Knights

import java.util.*;

public class nineknights {

	final public static int N = 5;
	final public static int NUMKNIGHTS = 9;

	public static void main(String[] args) {

		Scanner stdin = new Scanner(System.in);

		// Store the knights by a single index.
		ArrayList<Integer> knights = new ArrayList<Integer>();
		for (int i=0; i<N; i++) {
			String s = stdin.next();
			for (int j=0; j<N; j++)
				if (s.charAt(j) == 'k')
					knights.add(N*i+j);
		}

		System.out.println(solve(knights));
	}

	public static String solve(ArrayList<Integer> knights) {

		// Must have right #.
		if (knights.size() != NUMKNIGHTS) return "invalid";

		// Check all pairs.
		for (int i=0; i<knights.size(); i++) {
			for (int j=i+1; j<knights.size(); j++) {
				int dx = Math.abs(knights.get(i)/N - knights.get(j)/N);
				int dy = Math.abs(knights.get(i)%N - knights.get(j)%N);

				// Screen out invalid choices.
				if (dx == 1 && dy == 2) return "invalid";
				if (dx == 2 && dy == 1) return "invalid";
			}
		}

		// We made it.
		return "valid";
	}
}