Problem:
Score : 300 points

Problem Statement

We will call a string obtained by arranging the characters contained in a string a in some order, an anagram of a.

For example, greenbin is an anagram of beginner. As seen here, when the same character occurs multiple times, that character must be used that number of times.

Given are N strings s_1, s_2, \ldots, s_N. Each of these strings has a length of 10 and consists of lowercase English characters. Additionally, all of these strings are distinct. Find the number of pairs of integers i, j (1 \leq i < j \leq N) such that s_i is an anagram of s_j.

Constraints

2 \leq N \leq 10^5

s_i is a string of length 10.

Each character in s_i is a lowercase English letter.

s_1, s_2, \ldots, s_N are all distinct.

Input

Input is given from Standard Input in the following format:

N
s_1
s_2
:
s_N

Output

Print the number of pairs of integers i, j (1 \leq i < j \leq N) such that s_i is an anagram of s_j.

Sample Input 1

3
acornistnt
peanutbomb
constraint

Sample Output 1

1

s_1 = acornistnt is an anagram of s_3 = constraint. There are no other pairs i, j such that s_i is an anagram of s_j, so the answer is 1.

Sample Input 2

2
oneplustwo
ninemodsix

Sample Output 2

0

If there is no pair i, j such that s_i is an anagram of s_j, print 0.

Sample Input 3

5
abaaaaaaaa
oneplustwo
aaaaaaaaba
twoplusone
aaaabaaaaa

Sample Output 3

4

Note that the answer may not fit into a 32-bit integer type, though we cannot put such a case here.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

#pragma warning disable

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Text.RegularExpressions;


static class MainClass
{
    public static void Main(string[] args)
    {
        var n = Console.ReadLine().ToInt32();
        var ls = new List<string>();
        var dic = new Dictionary<Dictionary<char, int>, int>(new comperer());

        var count = 0l;
        for (int i = 0; i < n; i++)
        {
            var s = Console.ReadLine();
            ls.Add(s);
            var valueDic = new Dictionary<char, int>();
            foreach (var item in s)
            {
                if (valueDic.ContainsKey(item))
                    valueDic[item]++;
                else
                    valueDic.Add(item, 1);
            }

            if (dic.ContainsKey(valueDic))
            {
                count += dic[valueDic];
                dic[valueDic]++;
            }
            else
                dic.Add(valueDic, 1);
        }
        Console.WriteLine(count);
        Console.ReadLine();
    }

    class comperer : IEqualityComparer<Dictionary<char, int>>
    {
        public bool Equals(Dictionary<char, int> x, Dictionary<char, int> y)
        {
            if (x.Count != y.Count)
            {
                return false;
            }
            foreach (var item in x)
            {
                if (!y.ContainsKey(item.Key) || y[item.Key] != item.Value)
                {
                    return false;
                }
            }
            return true;
        }

        public int GetHashCode(Dictionary<char, int> obj)
        {
            var sum = 0;
            foreach (var item in obj)
            {
                var al = (int)Math.Pow(2,item.Key - 'a');
                var wa = item.Value;
                sum += al * wa;
            }
            return sum;
        }
    }



    public static int LowerBound<T>(this List<T> arr, int start, int end, T value, IComparer<T> comparer)
    {
        int low = start;
        int high = end;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (comparer.Compare(arr[mid], value) < 0)
                low = mid + 1;
            else
                high = mid;
        }
        return low;
    }

    public static int LowerBound<T>(this List<T> arr, T value) where T : IComparable
    {
        return LowerBound(arr, 0, arr.Count(), value, Comparer<T>.Default);
    }

    public static int UpperBound<T>(this List<T> arr, int start, int end, T value, IComparer<T> comparer)
    {
        int low = start;
        int high = end;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (comparer.Compare(arr[mid], value) <= 0)
                low = mid + 1;
            else
                high = mid;
        }
        return low;
    }

    public static int UpperBound<T>(this List<T> arr, T value)
    {
        return UpperBound(arr, 0, arr.Count(), value, Comparer<T>.Default);
    }


    #region
    public static int ParentCount;

    public static int[] Parents;
    public static int[] IfParentsChildrenCount;

    public static int[] Ranks;

    public static void InitializeUnionFind(int N)
    {
        Parents = new int[N];
        Ranks = new int[N];
        IfParentsChildrenCount = new int[N];
        for (int i = 0; i < N; i++)
        {
            Parents[i] = i;
            Ranks[i] = 0;
            IfParentsChildrenCount[i] = 1;
        }
        ParentCount = N + 1;
    }

    public static int Root(int a)
    {
        if (Parents[a] == a)
        {
            return a;
        }
        else
        {
            Parents[a] = Root(Parents[a]);
            return Parents[a];
        }
    }

    public static bool Same(int a, int b)
    {
        return Root(a) == Root(b);
    }

    public static void Unite(int a, int b)
    {
        var parentA = Root(a);
        var parentB = Root(b);
        if (parentA == parentB)
            return;
        if (Ranks[parentA] < Ranks[parentB])
        {
            Parents[parentA] = parentB;
            IfParentsChildrenCount[parentB] += IfParentsChildrenCount[parentA];
            ParentCount -= IfParentsChildrenCount[parentA];

            IfParentsChildrenCount[parentA] = 0;
        }
        else
        {
            Parents[parentB] = parentA;
            if (Ranks[parentA] == Ranks[parentB])
            {
                Ranks[parentA]++;
            }
            IfParentsChildrenCount[parentA] += IfParentsChildrenCount[parentB];
            ParentCount -= IfParentsChildrenCount[parentB];
            IfParentsChildrenCount[parentB] = 0;
        }
    }
    #endregion
    #region ライブラリ

    public static long ToInt64(this string str) => long.Parse(str);
    public static int ToInt32(this string str) => str == "" ? 0 : int.Parse(str);
    public static BigInteger ToBigInteger(this string str) => BigInteger.Parse(str);
    public static List<string> SplittedStringToList(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList();
    public static List<int> SplittedStringToInt32List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => int.Parse(x)).ToList();
    public static List<long> SplittedStringToInt64List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => long.Parse(x)).ToList();
    public static List<BigInteger> SplittedStringToBigInteger(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => BigInteger.Parse(x)).ToList();
    public const int INF = int.MaxValue / 4;
    public const long LONGINF = long.MaxValue / 2;
    public const int Mod1e9 = 1000000007;

    public static void PrintArray(char[,] array)
    {
        for (int i = 0; i < array.GetLength(0); i++)
        {
            var sb = new StringBuilder();
            for (int j = 0; j < array.GetLength(1); j++)
            {
                sb.Append(array[i, j]);
            }
            Console.WriteLine(sb.ToString());
        }
    }
    public static int Manhattan(int x1, int x2, int y1, int y2)
    {
        return Math.Abs(x1 - x2) + Math.Abs(y1 - y2);
    }

    public static int Manhattan(KeyValuePair<int, int> keyValuePair1, KeyValuePair<int, int> keyValuePair2)
    {
        return Manhattan(keyValuePair1.Key, keyValuePair2.Key, keyValuePair1.Value, keyValuePair2.Value);
    }

    public static Dictionary<T, int> ToCountedDictionary<T>(this IEnumerable<T> items)
    {
        var dic = new Dictionary<T, int>();
        foreach (var item in items)
        {
            if (dic.ContainsKey(item))
                dic[item]++;
            else
                dic.Add(item, 1);
        }
        return dic;
    }
    public static Dictionary<TKey, TValue> KeyValuePairListToDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> pairs)
    {
        var dic = new Dictionary<TKey, TValue>();
        foreach (var item in pairs)
        {
            dic.Add(item.Key, item.Value);
        }
        return dic;
    }

    public static long Sums(IEnumerable<int> list)
    {
        var sum = 0l;
        foreach (var item in list)
        {
            sum += Math.Abs(item);
        }
        return sum;
        #endregion
    }

    public static int[] dx = { -1, 1, 0, 0 };
    public static int[] dy = { 0, 0, 1, -1 };

    public static int[] dxx = { 0, 1, 1, 1, 0, -1, -1, -1 };
    public static int[] dyy = { 1, 1, 0, -1, -1, -1, 0, 1 };
}