# -*- coding: utf-8 -*-
import sys
import math
import os
import itertools
import string
import heapq
import _collections
from collections import Counter
from collections import defaultdict
from functools import lru_cache
import bisect
import re
import queue


class Scanner():
    @staticmethod
    def int():
        return int(sys.stdin.readline().rstrip())

    @staticmethod
    def string():
        return sys.stdin.readline().rstrip()

    @staticmethod
    def map_int():
        return [int(x) for x in Scanner.string().split()]

    @staticmethod
    def string_list(n):
        return [input() for i in range(n)]

    @staticmethod
    def int_list_list(n):
        return [Scanner.map_int() for i in range(n)]

    @staticmethod
    def int_cols_list(n):
        return [int(input()) for i in range(n)]


class Math():
    @staticmethod
    def gcd(a, b):
        if b == 0:
            return a
        return Math.gcd(b, a % b)

    @staticmethod
    def lcm(a, b):
        return (a * b) // Math.gcd(a, b)

    @staticmethod
    def roundUp(a, b):
        return -(-a // b)

    @staticmethod
    def toUpperMultiple(a, x):
        return Math.roundUp(a, x) * x

    @staticmethod
    def toLowerMultiple(a, x):
        return (a // x) * x

    @staticmethod
    def nearPow2(n):
        if n <= 0:
            return 0
        if n & (n - 1) == 0:
            return n
        ret = 1
        while(n > 0):
            ret <<= 1
            n >>= 1
        return ret

    @staticmethod
    def sign(n):
        if n == 0:
            return 0
        if n < 0:
            return -1
        return 1

    @staticmethod
    def isPrime(n):
        if n < 2:
            return False
        if n == 2:
            return True
        if n % 2 == 0:
            return False
        d = int(n ** 0.5) + 1
        for i in range(3, d + 1, 2):
            if n % i == 0:
                return False
        return True


MOD = int(1e09) + 7
INF = int(1e15)

T_MAX = int(1e05) + 1


def main():
    # sys.stdin = open("sample.txt")
    N, K = Scanner.map_int()
    T = defaultdict(list)
    for _ in range(N):
        t, d = Scanner.map_int()
        t -= 1
        T[t].append(d)
    for v in T.values():
        v.sort(reverse=True)
    M = []
    for v in T.values():
        M.append((v[0], 1))
        for i in range(1, len(v)):
            M.append((v[i], 0))
    M.sort(reverse=True)
    q = []
    x = 0
    y = 0
    for i in range(K):
        x += M[i][0]
        if M[i][1] == 0:
            heapq.heappush(q, M[i][0])
        y += M[i][1]
    ans = x + y * y
    for i in range(K, N):
        if M[i][1] == 1:
            x -= q.pop()
            x += M[i][0]
            y += 1
            ans = max(ans, x + y * y)
            if q == []:
                break
    print(ans)


if __name__ == "__main__":
    main()


### FIXED CODE ###

# -*- coding: utf-8 -*-
import sys
import math
import os
import itertools
import string
import heapq
import _collections
from collections import Counter
from collections import defaultdict
from functools import lru_cache
import bisect
import re
import queue


class Scanner():
    @staticmethod
    def int():
        return int(sys.stdin.readline().rstrip())

    @staticmethod
    def string():
        return sys.stdin.readline().rstrip()

    @staticmethod
    def map_int():
        return [int(x) for x in Scanner.string().split()]

    @staticmethod
    def string_list(n):
        return [input() for i in range(n)]

    @staticmethod
    def int_list_list(n):
        return [Scanner.map_int() for i in range(n)]

    @staticmethod
    def int_cols_list(n):
        return [int(input()) for i in range(n)]


class Math():
    @staticmethod
    def gcd(a, b):
        if b == 0:
            return a
        return Math.gcd(b, a % b)

    @staticmethod
    def lcm(a, b):
        return (a * b) // Math.gcd(a, b)

    @staticmethod
    def roundUp(a, b):
        return -(-a // b)

    @staticmethod
    def toUpperMultiple(a, x):
        return Math.roundUp(a, x) * x

    @staticmethod
    def toLowerMultiple(a, x):
        return (a // x) * x

    @staticmethod
    def nearPow2(n):
        if n <= 0:
            return 0
        if n & (n - 1) == 0:
            return n
        ret = 1
        while(n > 0):
            ret <<= 1
            n >>= 1
        return ret

    @staticmethod
    def sign(n):
        if n == 0:
            return 0
        if n < 0:
            return -1
        return 1

    @staticmethod
    def isPrime(n):
        if n < 2:
            return False
        if n == 2:
            return True
        if n % 2 == 0:
            return False
        d = int(n ** 0.5) + 1
        for i in range(3, d + 1, 2):
            if n % i == 0:
                return False
        return True


MOD = int(1e09) + 7
INF = int(1e15)

T_MAX = int(1e05) + 1


def main():
    # sys.stdin = open("sample.txt")
    N, K = Scanner.map_int()
    T = defaultdict(list)
    for _ in range(N):
        t, d = Scanner.map_int()
        t -= 1
        T[t].append(d)
    for v in T.values():
        v.sort(reverse=True)
    M = []
    for v in T.values():
        M.append((v[0], 1))
        for i in range(1, len(v)):
            M.append((v[i], 0))
    M.sort(reverse=True)

    q = []
    x = 0
    y = 0
    for i in range(K):
        x += M[i][0]
        y += M[i][1]
        if M[i][1] == 0:
            heapq.heappush(q, M[i][0])
    ans = x + y * y
    for i in range(K, N):
        if q == []:
            break
        if M[i][1] == 1:
            x -= heapq.heappop(q)
            x += M[i][0]
            y += 1
            ans = max(ans, x + y * y)
    print(ans)


if __name__ == "__main__":
    main()