using System;

public class Program

{

    public static void Main()

    {

        var solution = new Solution();

        var a = "aba";

        var b = "cdc";

        Console.WriteLine(solution.FindLUSlength(a,b));

    }

}

​

public class Solution {

    public int FindLUSlength(string a, string b) {

        return a.Equals(b) ? -1 : Math.Max(a.Length, b.Length);

    }

}