using System;

// To execute C#, please define "static void Main" on a class
// named Solution.

class Solution {
    
    static string ReverseString(string inputString) {
        if (inputString.Length <= 1) 
            return inputString;
        else
            return ReverseString(inputString.Substring(1, inputString.Length - 1)) + inputString[0];
    }
    
    static void Main(string[] args) {
        
        var firstName = "Tom";
        var lastName = "Smith";
        var fullName = firstName + " " + lastName;
        
        Console.WriteLine(ReverseString(firstName));
        Console.WriteLine(ReverseString("Google"));
    }
}

using System;

class Solution {
    
    static string Sort(string s) {
        char[] content = s.ToCharArray();
        Array.Sort(content);
        return new string(content);
    }
    
    static bool Permutation(string s, string t) {
        if (s.Length != t.Length) {
            return false;   
        } else {
            return Sort(s).Equals(Sort(t));   
        }
    }
    
    static void Main(string[] args) {

        Console.WriteLine(Permutation("taco", "cato"));
        Console.WriteLine(Permutation("taco", "catt"));
    }
}

using System;

class Solution {
    

    static string Reverse(string str) {
        string stringBuffer = String.Empty;
        int length = str.Length;
        
        for (int i = length - 1; i >= 0; i--) {
            stringBuffer += str[i];
        }
        
        return stringBuffer;
    }
    
    static void Main(string[] args) {

        Console.WriteLine(Reverse("taco"));

    }
}