using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var N = sc.ReadInt();
        var K = sc.ReadInt();
        var tds = new Tuple<long, long>[N];
        for (int i = 0; i < N; i++)
        {
            var t = Tuple.Create(sc.ReadLong(), sc.ReadLong());
            tds[i] = t;
        }
        tds = tds.OrderByDescending(x => x.Item2).ToArray();

        long tCount = 0;
        var types = new HashMap<long, long>();
        var xxx = new List<Tuple<long, long>>();
        for (int i = 0; i < K; i++)
        {
            types[tds[i].Item1]++;
            if (types[tds[i].Item1] > 1)
            {
                xxx.Add(tds[i]);
            }
            else
            {
                tCount++;
            }
        }
        // 重複している者のうち小さいものから順に並べたデータ
        xxx = xxx.OrderBy(x => x.Item2).ToList();

        long sum = tds.Take(K).Sum(x => x.Item2);
        long bonus = tCount * tCount;
        long ans = sum + bonus;

        // 順番に種類を増やしてく
        foreach (var td in tds.Skip(K))
        {
            var newType = td.Item1;
            if (types[newType] == 0 && xxx.Count > 0)
            {
                types[newType]++;
                var ri = xxx[0];
                xxx.RemoveAt(0);
                sum -= (ri.Item2 - td.Item2);
                tCount++;
                checked
                {
                    bonus = tCount * tCount;
                }
                ans = Math.Max(ans, sum + bonus);
            }
        }

        Console.WriteLine(ans);
    }
    static Scanner sc = new Scanner();
}

class HashMap<K, V> : Dictionary<K, V> where V : new()
{
    private V DefaltValue = new V();
    public HashMap() { }
    public HashMap(V defaultValue)
    {
        this.DefaltValue = new V();
    }
    new public V this[K i]
    {
        get
        {
            V v;
            return TryGetValue(i, out v) ? v : base[i] = this.DefaltValue;
        }
        set { base[i] = value; }
    }
}

class Scanner
{
    string[] S = new string[0];
    int Index = 0;
    char[] Separators = new char[] { ' ' };

    public string Next()
    {
        if (this.Index < this.S.Length) return this.S[this.Index++];
        var line = "";
        while (line == "") line = Console.ReadLine();
        this.S = line.Split(this.Separators, StringSplitOptions.RemoveEmptyEntries);
        if (this.S.Length == 0) return this.Next();
        this.Index = 0;
        return this.S[this.Index++];
    }
    public string ReadStr()
    {
        return this.Next();
    }
    public char ReadChar()
    {
        return this.Next()[0];
    }
    public int ReadInt()
    {
        return int.Parse(this.Next());
    }
    public uint ReadUInt()
    {
        return uint.Parse(this.Next());
    }
    public long ReadLong()
    {
        return long.Parse(this.Next());
    }
    public double ReadDouble()
    {
        return double.Parse(this.Next());
    }
    public Tuple<int, int> ReadTup()
    {
        return Tuple.Create(this.ReadInt(), this.ReadInt());
    }
    public Tuple<int, int, int> ReadTup3()
    {
        return Tuple.Create(this.ReadInt(), this.ReadInt(), this.ReadInt());
    }
    public Tuple<int, int, int, int> ReadTup4()
    {
        return Tuple.Create(this.ReadInt(), this.ReadInt(), this.ReadInt(), this.ReadInt());
    }
    public int[] ReadIntArray(int n)
    {
        var array = new int[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadInt();
        }
        return array;
    }
    public long[] ReadLongArray(int n)
    {
        var array = new long[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadLong();
        }
        return array;
    }
    public double[] ReadDoubleArray(int n)
    {
        var array = new double[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadDouble();
        }
        return array;
    }
    public char[] ReadCharArray(int n)
    {
        var array = new char[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadChar();
        }
        return array;
    }
    public string[] ReadStrArray(int n)
    {
        var array = new string[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadStr();
        }
        return array;
    }
    public Tuple<int, int>[] ReadTupArray(int n)
    {
        var array = new Tuple<int, int>[n];
        for (int i = 0; i < n; i++)
        {
            array[i] = this.ReadTup();
        }
        return array;
    }
    public Tuple<int, int, int>[] ReadTup3Array(int n)
    {
        var array = new Tuple<int, int, int>[n];
        for (int i = 0; i < n; i++)
        {
            array[i] = this.ReadTup3();
        }
        return array;
    }
    public Tuple<int, int, int, int>[] ReadTup4Array(int n)
    {
        var array = new Tuple<int, int, int, int>[n];
        for (int i = 0; i < n; i++)
        {
            array[i] = this.ReadTup4();
        }
        return array;
    }
}


Measured memory_bytes: 34500