import java.io.*; // for handling input/output
import java.util.*; // contains Collections framework

// don't change the name of this class
// you can add inner classes if needed
class Main {
	public static void main (String[] args) {
		Scanner scan = new Scanner(System.in);
		int t = scan.nextInt();

		

		while(t>0)
		{
			int[] freqCounter = new int[26];
			String str = scan.next();

			for(int i = 0; i < str.length(); i++)
			{
				freqCounter[str.charAt(i) - 'a']++;
			}

			boolean flag = true;
			for(int i = 0; i < str.length(); i++)
			{
				if(freqCounter[str.charAt(i)-'a'] > 1){
					System.out.println(str.charAt(i));
					flag = false;
					break;
				}
			}

			if(flag)
			{
				System.out.println(-1);
			}

			t--;
		}

	}
}