using System;

​

class GFG 

{ 

    /** 

    * permutation function 

    * @param str string to  

       calculate permutation for 

    * @param l starting index 

    * @param r end index 

    */

    private static void Permute(String str, int l, int r) 

    { 

        if (l == r) 

            Console.WriteLine(str); 

        else

        { 

            for (int i = l; i <= r; i++) 

            { 

                str = Swap(str, l, i); 

                Permute(str, l + 1, r); 

                str = Swap(str, l, i); // Backtracking

            } 

        } 

    } 

    /** 

    * Swap Characters at position 

    * @param a string value 

    * @param i position 1 

    * @param j position 2 

    * @return swapped string 

    */

    public static String Swap(String a, int i, int j) 

    { 

        char temp; 

        char[] charArray = a.ToCharArray(); 

        temp = charArray[i] ; 

        charArray[i] = charArray[j]; 

        charArray[j] = temp; 

        string s = new string(charArray); 

        return s; 

    } 

    // Driver Code 

    public static void Main() 

    { 

        String str = "ABC"; 

        int n = str.Length; 

        Permute(str, 0, n-1); 

    } 

} 

// This code is contributed by mits