// Arup Guha
// 4/7/2018
// Solution to 2018 Code Jam Qualification Problem: Trouble Sort

import java.util.*;
import java.io.*;

public class Solution {

	public static void main(String[] args) throws Exception {

		BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
		int nC = Integer.parseInt(stdin.readLine().trim());

		// Process each case
		for (int loop=1; loop<=nC; loop++) {

			int n = Integer.parseInt(stdin.readLine().trim());
			int[] orig = new int[n];
			StringTokenizer tok = new StringTokenizer(stdin.readLine());
			for (int i=0; i<n; i++)
				orig[i] = Integer.parseInt(tok.nextToken());

			// Separate out into odd and even arrays.
			int[] even = new int[(n+1)/2];
			for (int i=0; i<even.length; i++)
				even[i] = orig[2*i];
			int[] odd = new int[n/2];
			for (int i=0; i<odd.length; i++)
				odd[i] = orig[2*i+1];

			// Their algorithm sorts both of these separately.
			Arrays.sort(even);
			Arrays.sort(odd);

			// Reform their answer...
			int[] res = new int[n];
			for (int i=0; i<even.length; i++)
				res[2*i] = even[i];
			for (int i=0; i<odd.length; i++)
				res[2*i+1] = odd[i];

			// Look for inversion.
			int error = -1;
			for (int i=0; i<n-1; i++) {
				if (res[i] > res[i+1]) {
					error = i;
					break;
				}
			}

			// Ta da!
			if (error == -1)
				System.out.println("Case #"+loop+": OK");
			else
				System.out.println("Case #"+loop+": "+error);

		}
	}
}