import java.io.PrintStream;
import java.util.Scanner;

public class Login
{
	public static void main(String[] args)
	{
		Scanner input = new Scanner(System.in);
		PrintStream output = System.out;
		
		output.print("login: ");
		String line = input.nextLine();
		final String PATTERN ="cse(\\d){5}";
		if (line.matches(PATTERN))
		{
			output.println("valid");
		}
		else
		{
			output.println("invalid");
		}
	}
}