using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text;
using static System.Math;
using static System.Array;
using static AtCoder.Tool;
namespace AtCoder
{
    class AC
    {
        const int MOD = 1000000007;
        const int INF = int.MaxValue / 2;
        const long SINF = long.MaxValue / 2;
        const double EPS = 1e-8;
        static readonly int[] dx = { 0, 1, 0, -1 };
        static readonly int[] dy = { 1, 0, -1, 0 };

        
        static void Main(string[] args)
        {
            //var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            //Console.SetOut(sw);
            var cin = new Scanner();

            var input = cin.SplitRead();
            int N = input[0];
            int K = input[1];

            var dic = new Dictionary<int, int>();

            long type = 0;
            long dsum = 0;
            var s = new PriorityQueue<Sushi>(true);

            for(var i = 0; i < N; i++)
            {
                var td = cin.SplitReadL();
                s.Enqueue(new Sushi((int)td[0], td[1]));
            }

            var chout = new PriorityQueue<Sushi>(false);

            for(var i = 0; i < K; i++)
            {
                var su = s.Dequeue();
                if (!dic.ContainsKey(su.t))
                {
                    dic[su.t] = 1;
                    type++;
                }
                else
                {
                    dic[su.t]++;
                    chout.Enqueue(su);
                }
                dsum += su.d;
            }

            var ans = new List<long>();
            ans.Add(dsum + (type * type));


            for(var i = 0; i < N - K; i++)
            {
                if (chout.CountItem() == 0) { break; }
                var su = s.Dequeue();
                if (dic.ContainsKey(su.t)) { continue; }

                var sout = chout.Dequeue();
                dic[su.t] = 1;
                type++;
                dsum += su.d - sout.d;
                ans.Add(dsum + (type * type));
            }


            Console.WriteLine(ans.Max());

            



            

            //Console.Out.Flush();
        }
        struct Sushi:IComparable<Sushi>
        {
            public int t;
            public long d;
            public Sushi(int ti,long di)
            {
                t = ti;
                d = di;
            }
            public int CompareTo(Sushi other)
            {
                return d.CompareTo(other.d);
            }
        }
        
    }
    public class PriorityQueue<T> where T : IComparable<T>
    {

        private List<T> Q;
        private readonly int r;

        public PriorityQueue(bool ascending)
        {
            if (ascending)
            {
                r = 1;
            }
            else
            {
                r = -1;
            }
            Q = new List<T>();
        }


        private void PushHeap(List<T> list, T item)
        {
            int n = list.Count();
            list.Add(item);

            while (n != 0)
            {
                int pIndex = (n - 1) / 2;

                if (list[n].CompareTo(list[pIndex]) * r > 0)
                {
                    Swap(Q, n, pIndex);
                }
                else { break; }

                n = pIndex;
            }
        }

        private void PopHeap(List<T> list)
        {
            int n = list.Count() - 1;
            list[0] = list[n];
            list.RemoveAt(n);

            int cur = 0;
            int comp;

            while (2 * cur + 1 <= n - 1)
            {
                int c1 = 2 * cur + 1;
                int c2 = 2 * (cur + 1);
                if (c1 == n - 1)
                {
                    comp = c1;
                }
                else
                {

                    comp = list[c1].CompareTo(list[c2]) * r > 0 ? c1 : c2;
                }

                if (list[cur].CompareTo(list[comp]) * r < 0)
                {
                    Swap(Q, cur, comp);
                }
                else { break; }

                cur = comp;
            }
        }

        private void Swap(List<T> list, int a, int b)
        {
            T keep = list[a];
            list[a] = list[b];
            list[b] = keep;
        }



        public void Enqueue(T value)
        {
            PushHeap(Q, value);
        }

        public T Dequeue()
        {
            T ret = Q[0];
            PopHeap(Q);
            return ret;
        }

        public T Peek()
        {
            return Q[0];
        }

        public int CountItem()
        {
            return Q.Count();
        }
    }

    public class Scanner
    {
        public int[] SplitRead()
        {
            int[] array = Console.ReadLine().Split().Select(int.Parse).ToArray();
            return array;
        }
        public long[] SplitReadL()
        {
            long[] array = Console.ReadLine().Split().Select(long.Parse).ToArray();
            return array;
        }
    }

    public static class Tool
    {
        static public void Initialize<T>(ref T[] array, T initialvalue)
        {
            for (var i = 0; i < array.Length; i++)
            {
                array[i] = initialvalue;
            }
        }
    }
}


Measured memory_bytes: 24504