static string rot(string s, int n) => return string.Concat(s.Select(x => (char)(x >= 'A' && x <= 'Z' ? (x + n > 'Z' ? x - 26 + n : x + n) : x >= 'a' && x <= 'z' ? (x + n > 'z' ? x - 26 + n : x + n) : x)));