Problem:
Score : 300 points

Problem Statement

Takahashi has N balls. Initially, an integer A_i is written on the i-th ball.

He would like to rewrite the integer on some balls so that there are at most K different integers written on the N balls.

Find the minimum number of balls that Takahashi needs to rewrite the integers on them.

Constraints

1 \leq K \leq N \leq 200000

1 \leq A_i \leq N

All input values are integers.

Input

Input is given from Standard Input in the following format:

N K
A_1 A_2 ... A_N

Output

Print the minimum number of balls that Takahashi needs to rewrite the integers on them.

Sample Input 1

5 2
1 1 2 2 5

Sample Output 1

1

For example, if we rewrite the integer on the fifth ball to 2, there are two different integers written on the balls: 1 and 2.
On the other hand, it is not possible to rewrite the integers on zero balls so that there are at most two different integers written on the balls, so we should print 1.

Sample Input 2

4 4
1 1 2 2

Sample Output 2

0

Already in the beginning, there are two different integers written on the balls, so we do not need to rewrite anything.

Sample Input 3

10 3
5 1 3 2 4 1 1 2 3 4

Sample Output 3

3

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

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Math;
using static AtCoderTemplate.MyExtensions;
using static AtCoderTemplate.MyInputOutputs;
using static AtCoderTemplate.MyNumericFunctions;

namespace AtCoderTemplate {
    public class Program {
        public static void Main (string[] args) {
            var NK = ReadInts ();
            var N = NK[0];
            var K = NK[1];
            var A = ReadInts ();

            var groups = A.GroupBy (x => x);
            var M = groups.Count ();
            if (M <= K) {
                Print (0);
            } else {
                var counts = groups.Select (group => group.Count ()).OrderBy (x => x);
                var ans = counts.Take (M - K).Sum ();
                Print (ans);
            }
        }
    }

    static class MyInputOutputs {
        /* Input & Output*/
        public static int ReadInt () {
            return int.Parse (Console.ReadLine ());
        }
        public static long ReadLong () {
            return long.Parse (Console.ReadLine ());
        }
        public static List<int> ReadInts () {
            return Console.ReadLine ().Split (' ').Select (c => int.Parse (c)).ToList ();
        }
        public static List<long> ReadLongs () {
            return Console.ReadLine ().Split (' ').Select (c => long.Parse (c)).ToList ();
        }
        public static List<List<int>> ReadIntColumns (int n) {
            /*
            入力例
            A1 B1
            A2 B2
            ...
            An Bn

            出力例
            [[A1,A2,...,An], [B1,B2,...,Bn]]
            */
            var rows = Enumerable.Range (0, n).Select (i => ReadInts ()).ToList ();
            var m = rows.FirstOrDefault ()?.Count () ?? 0;
            return Enumerable.Range (0, m).Select (i => rows.Select (items => items[i]).ToList ()).ToList ();
        }
        public static List<List<long>> ReadLongColumns (int n) {
            /*
            入力例
            A1 B1
            A2 B2
            ...
            An Bn

            出力例
            [[A1,A2,...,An], [B1,B2,...,Bn]]
            */
            var rows = Enumerable.Range (0, n).Select (i => ReadLongs ()).ToList ();
            var m = rows.FirstOrDefault ()?.Count () ?? 0;
            return Enumerable.Range (0, m).Select (i => rows.Select (items => items[i]).ToList ()).ToList ();
        }

        public static void Print<T> (T item) {
            Console.WriteLine (item);
        }
        public static void PrintIf<T1, T2> (bool condition, T1 trueResult, T2 falseResult) {
            if (condition) {
                Console.WriteLine (trueResult);
            } else {
                Console.WriteLine (falseResult);
            }
        }

        public static void PrintRow<T> (IEnumerable<T> list) {
            /* 横ベクトルで表示
            A B C D ...
            */
            if (!list.IsEmpty ()) {
                Console.Write (list.First ());
                foreach (var item in list.Skip (1)) {
                    Console.Write ($" {item}");
                }
            }
            Console.Write ("\n");
        }
        public static void PrintColomn<T> (IEnumerable<T> list) {
            /* 縦ベクトルで表示
            A
            B
            C
            D
            ...
            */
            foreach (var item in list) {
                Console.WriteLine (item);
            }
        }
        public static void Print2DArray<T> (IEnumerable<IEnumerable<T>> sources) {
            foreach (var row in sources) {
                PrintRow (row);
            }
        }
    }

    static class MyNumericFunctions {
        public static bool isEven (int a) {
            return a % 2 == 0;
        }
        public static bool isEven (long a) {
            return a % 2 == 0;
        }
        public static bool isOdd (int a) {
            return !isEven (a);
        }
        public static bool isOdd (long a) {
            return !isEven (a);
        }

        public static long nPk (int n, int k) {
            if (k > n) {
                return 0;
            } else {
                return Enumerable.Range (n - k + 1, k).Aggregate ((long) 1, ((i, m) => i * m));
            }
        }
        public static long Fact (int n) {
            return nPk (n, n);
        }
        public static long nCk (int n, int k) {
            if (k > n) {
                return 0;
            } else {
                return nPk (n, k) / Fact (k);
            }
        }
        // 最大公約数

        public static long GCD (long m, long n) {
            if (m < n) {
                return GCD (n, m);
            } else if (n == 0) {
                return m;
            } else {
                return GCD (n, m % n);
            }
        }
        // 最小公倍数
        public static long LCM (long m, long n) {
            if (m < n) {
                return LCM (n, m);
            } else {
                return (m * n) / GCD (m, n);
            }
        }
    }

    static class MyExtensions {
        // AppendとPrependが、.NET Standard 1.6からの追加で、Mono 4.6.2 はそれに対応して仕様はあるが、実装がない
        public static IEnumerable<T> Append<T> (this IEnumerable<T> source, T element) {
            return source.Concat (Enumerable.Repeat (element, 1));
        }

        public static IEnumerable<T> Prepend<T> (this IEnumerable<T> source, T element) {
            return Enumerable.Repeat (element, 1).Concat (source);
        }

        // TakeLastとSkipLastが、.Net Standard 2.1からの追加で、Mono 4.6.2 はそれに対応していない
        public static IEnumerable<T> TakeLast<T> (this IEnumerable<T> source, int count) {
            return source.Skip (source.Count () - count);
        }

        public static IEnumerable<T> SkipLast<T> (this IEnumerable<T> source, int count) {
            return source.Take (source.Count () - count);
        }

        public static bool IsEmpty<T> (this IEnumerable<T> source) {
            return !source.Any ();
        }

        /// <summary>
        /// インデックスiの位置の要素からk個取り除く
        /// O(N)
        /// </summary>
        public static IEnumerable<T> TakeAwayRange<T> (this IEnumerable<T> source, int i, int count) {
            return source.Take (i).Concat (source.Skip (i + count));
        }

        /// <summary>
        /// インデックスiの位置の要素を取り除く
        /// O(N)
        /// </summary>
        public static IEnumerable<T> TakeAwayAt<T> (this IEnumerable<T> source, int i) {
            return source.TakeAwayRange (i, 1);
        }

        /// <summary>
        /// インデックスiの位置にシーケンスを挿入する
        /// O(N + K)
        /// </summary>
        public static IEnumerable<T> InsertEnumAt<T> (this IEnumerable<T> source, int i, IEnumerable<T> inserted) {
            return source.Take (i).Concat (inserted).Concat (source.Skip (i));
        }

        /// <summary>
        /// 順列を得る
        /// O(N!)
        /// </summary>
        public static IEnumerable<IEnumerable<T>> Perm<T> (this IEnumerable<T> source, int n) {
            if (n == 0 || source.IsEmpty () || source.Count () < n) {
                return Enumerable.Empty<IEnumerable<T>> ();
            } else if (n == 1) {
                return source.Select (i => new List<T> { i });
            } else {
                var nexts = source.Select ((x, i) =>
                    new { next = source.Take (i).Concat (source.Skip (i + 1)), selected = source.Take (i + 1).Last () });
                return nexts.SelectMany (next => Perm (next.next, n - 1).Select (item => item.Prepend (next.selected)));
            }
        }

        /// <summary>
        /// シーケンスの隣り合う要素を2引数の関数に適用したシーケンスを得る
        /// </summary>
        /// <para>O(N)</para>
        /// <param name="source">元のシーケンス</param>
        /// <param name="func">2引数関数</param>
        /// <example>[1,2,3,4].MapAdjacent(f) => [f(1,2), f(2,3), f(3,4)]</example>
        public static IEnumerable<TR> MapAdjacent<T1, TR> (this IEnumerable<T1> source, Func<T1, T1, TR> func) {
            var list = source.ToList ();
            return Enumerable.Range (1, list.Count - 1)
                .Select (i => func (list[i], list[i - 1]));
        }

        /// <summary>
        /// 累積項を要素にもつシーケンスを得る(初項は、first)
        /// <para>O(N)</para>
        /// </summary>
        /// <param name="source">元のシーケンス</param>
        /// <param name="func">2引数関数f</param>
        /// <param name="first">func(first, source[0])のための初項</param>
        /// <example> [1,2,3].Scanl1(f,0) => [0, f(0,1), f(f(0,1),2), f(f(f(0,1),2),3)]</example>
        public static IEnumerable<TR> Scanl<T, TR> (this IEnumerable<T> source, TR first, Func<TR, T, TR> func) {
            var list = source.ToList ();
            var result = new List<TR> { first };
            foreach (var i in Enumerable.Range (0, source.Count ())) {
                result.Add (func (result[i], list[i]));
            }
            return result;
        }
        /// <summary>
        /// 累積項を要素にもつシーケンスを得る（初項は、source.First()）
        /// <para>O(N)</para>
        /// </summary>
        /// <param name="source">元のシーケンス</param>
        /// <param name="func">2引数関数f</param>
        /// <example> [1,2,3].Scanl1(f) => [1, f(1,2), f(f(1,2),3)]</example>
        public static IEnumerable<T> Scanl1<T> (this IEnumerable<T> source, Func<T, T, T> func) {
            var list = source.ToList ();
            var result = new List<T> { list[0] };
            foreach (var i in Enumerable.Range (1, source.Count () - 1)) {
                result.Add (func (result[i - 1], list[i]));
            }
            return result;
        }

        /// <summary>
        /// 昇順にソートしたインデックスを得る
        /// </summary>
        /// <para>O(N * log N)</para>
        public static IEnumerable<int> SortIndex<T> (this IEnumerable<T> source) {
            return source
                .Select ((item, i) => new { Item = item, Index = i })
                .OrderBy (x => x.Item)
                .Select (x => x.Index);
        }
    }
}