Първо оправи отварящите и затварящи скоби! Няма как да мине като липсват :)
 {
    {
       {
           { 
            var word1 = (Console.ReadLine());
            var word2 = (Console.ReadLine());
            word1 = word1.ToLower();
            word2 = word2.ToLower();
            if (word1 == word2)
            {
                Console.WriteLine("yes");
            }
            else
            {
                Console.WriteLine("no");
            }
        }
    }
}

A compile time error occurred.

Compilation result:

Compiled file is missing. Compiler output: ...\tmp96CD.tmp(1,2): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(7,13): error CS0116: A namespace cannot directly contain members such as fields or methods
...\tmp96CD.tmp(7,19): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(7,27): error CS0116: A namespace cannot directly contain members such as fields or methods
...\tmp96CD.tmp(7,35): error CS8124: Tuple must contain at least two elements.
...\tmp96CD.tmp(7,36): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(8,13): error CS0116: A namespace cannot directly contain members such as fields or methods
...\tmp96CD.tmp(8,19): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(8,27): error CS0116: A namespace cannot directly contain members such as fields or methods
...\tmp96CD.tmp(8,35): error CS8124: Tuple must contain at least two elements.
...\tmp96CD.tmp(8,36): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(9,23): error CS8124: Tuple must contain at least two elements.
...\tmp96CD.tmp(9,23): error CS1026: ) expected
...\tmp96CD.tmp(9,23): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(9,26): error CS0116: A namespace cannot directly contain members such as fields or methods
...\tmp96CD.tmp(9,31): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(11,25): error CS0116: A namespace cannot directly contain members such as fields or methods
...\tmp96CD.tmp(11,35): error CS1031: Type expected
...\tmp96CD.tmp(11,35): error CS8124: Tuple must contain at least two elements.
...\tmp96CD.tmp(11,35): error CS1026: ) expected
...\tmp96CD.tmp(11,35): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(12,13): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(13,13): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(15,25): error CS0116: A namespace cannot directly contain members such as fields or methods
...\tmp96CD.tmp(15,35): error CS1031: Type expected
...\tmp96CD.tmp(15,35): error CS8124: Tuple must contain at least two elements.
...\tmp96CD.tmp(15,35): error CS1026: ) expected
...\tmp96CD.tmp(15,35): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(16,13): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(17,9): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(18,5): error CS1022: Type or namespace definition, or end-of-file expected
...\tmp96CD.tmp(19,1): error CS1022: Type or namespace definition, or end-of-file expected

Кода на stefanivanov95 е коректен, нали копираш в judge и началото на кода

namespace _
{
    class Program
    {
        static void Main(string[] args)
        {

Кода който постнах си работи, но системата не го приема