Problem:
Score : 500 points

Problem Statement

You have a string A = A_1 A_2 ... A_n consisting of lowercase English letters.

You can choose any two indices i and j such that 1 \leq i \leq j \leq n and reverse substring A_i A_{i+1} ... A_j.

You can perform this operation at most once.

How many different strings can you obtain?

Constraints

1 \leq |A| \leq 200,000

A consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

A

Output

Print the number of different strings you can obtain by reversing any substring in A at most once.

Sample Input 1

aatt

Sample Output 1

5

You can obtain aatt (don't do anything), atat (reverse A[2..3]), atta (reverse A[2..4]), ttaa (reverse A[1..4]) and taat (reverse A[1..3]).

Sample Input 2

xxxxxxxxxx

Sample Output 2

1

Whatever substring you reverse, you'll always get xxxxxxxxxx.

Sample Input 3

abracadabra

Sample Output 3

44

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AtCoder {
	class Program {
		#region Reserve
		static int cin() { return cin(-1); }
		static int cin(int D) {
			string s = Console.ReadLine();
			if (string.IsNullOrEmpty(s))
				return D;
			return int.Parse(s);
		}
		static long cln(long D = -1) {
			string s = Console.ReadLine();
			if (string.IsNullOrEmpty(s))
				return D;
			return long.Parse(s);
		}
		static int[] cins(char spliter) {
			string s = Console.ReadLine();
			if (string.IsNullOrEmpty(s))
				return new int[] { };
			string[] ss = s.Split(spliter);
			var Res = new int[ss.Length];
			for (int i = 0; i < ss.Length; i++)
				Res[i] = int.Parse(ss[i]);
			return Res;
		}
		static int[] cins() { return cins(' '); }
		static void print(object j) { Console.WriteLine(j.ToString()); }
		static void print(string j) { Console.WriteLine(j); }
		static string read() { return Console.ReadLine(); }
		#endregion

		static void Main(string[] args) {
			var A = read();
			var G = new int[26];
			foreach (char f in A) G[f - 97]++;
			long Res = A.Length * (A.Length - 1) / 2 + 1;
			Res -= G.Sum(j => j * (j - 1) / 2);
			print(Res);
			read();
		}
	}
}