// Original C++ solution (slower):
#include<bits/stdc++.h>

using namespace std;

typedef long long ll;

#define rep(i, n) for(int i = 0; i < (n); i++)

#define rep1(i, n) for(int i = 1; i <= (n); i++)

#define co(x) cout << (x) << "\n"

#define cosp(x) cout << (x) << " "

#define ce(x) cerr << (x) << "\n"

#define cesp(x) cerr << (x) << " "

#define pb push_back

#define mp make_pair

#define Would

#define you

#define please



void pakuri_sort(int N, int A[]) {

	const int b = 8;

	int tmp[100001];

	rep(k, 4) {

		int kazu[1 << b] = {}, kazu2[1 << b] = {};

		rep(i, N) kazu[A[i] >> k * b & ((1 << b) - 1)]++;

		rep(i, (1 << b) - 1) kazu[i + 1] += kazu[i];

		for (int i = N - 1; i >= 0; i--) tmp[--kazu[A[i] >> k * b & ((1 << b) - 1)]] = A[i];

		k++;

		rep(i, N) kazu2[tmp[i] >> k * b & ((1 << b) - 1)]++;

		rep(i, (1 << b) - 1) kazu2[i + 1] += kazu2[i];

		for (int i = N - 1; i >= 0; i--) A[--kazu2[tmp[i] >> k * b & ((1 << b) - 1)]] = tmp[i];

	}

}



int main() {

	cin.tie(0);

	ios::sync_with_stdio(false);



	int N, K;

	cin >> N >> K;

	int saidai[100000] = {};

	int shurui = 0;

	int sonota[100001];

	int k = 0;

	rep(i, N) {

		int t, d;

		cin >> t >> d;

		t--;

		if (!saidai[t]) {

			shurui++;

			saidai[t] = d;

		}

		else {

			if (saidai[t] < d) {

				swap(saidai[t], d);

			}

			sonota[k++] = d;

		}

	}



	pakuri_sort(100000, saidai);

	pakuri_sort(k, sonota);



	ll sonota2[100000];

	sonota2[k - 1] = sonota[k - 1];

	for (int i = k - 1; i >= 1; i--) {

		sonota2[i - 1] = sonota2[i] + sonota[i - 1];

	}



	ll kari = 0;

	ll kotae = 0;

	for (int i = 1; i <= min(K, shurui); i++) {

		kari += saidai[100000 - i];

		ll kari2 = kari;

		if (K - i > 0 && 0 <= k - K + i) kari2 += sonota2[k - K + i];

		kari2 += 1ll * i * i;

		kotae = max(kotae, kari2);

	}



	printf("%lld", kotae);



	Would you please return 0;

}

// Optimized solution to the same problem (faster):
//#include<bits/stdc++.h>

#include<cstdio>

#include<algorithm>

using namespace std;

typedef long long ll;

#define rep(i, n) for(int i = 0; i < (n); i++)

#define rep1(i, n) for(int i = 1; i <= (n); i++)

#define co(x) cout << (x) << "\n"

#define cosp(x) cout << (x) << " "

#define ce(x) cerr << (x) << "\n"

#define cesp(x) cerr << (x) << " "

#define pb push_back

#define mp make_pair

#define Would

#define you

#define please



const int cm = 1 << 17;

char cn[cm], * ci = cn + cm, ct;

inline char getcha() {

	if (ci - cn == cm) { fread(cn, 1, cm, stdin); ci = cn; }

	return *ci++;

}

inline int getint() {

	int A = 0;

	if (ci - cn + 16 > cm) while ((ct = getcha()) >= '0') A = A * 10 + ct - '0';

	else while ((ct = *ci++) >= '0') A = A * 10 + ct - '0';

	return A;

}



void pakuri_sort(int N, int A[]) {

	const int b = 8;

	int tmp[100001];

	rep(k, 4) {

		int kazu[1 << b] = {}, kazu2[1 << b] = {};

		rep(i, N) kazu[A[i] >> k * b & ((1 << b) - 1)]++;

		rep(i, (1 << b) - 1) kazu[i + 1] += kazu[i];

		for (int i = N - 1; i >= 0; i--) tmp[--kazu[A[i] >> k * b & ((1 << b) - 1)]] = A[i];

		k++;

		rep(i, N) kazu2[tmp[i] >> k * b & ((1 << b) - 1)]++;

		rep(i, (1 << b) - 1) kazu2[i + 1] += kazu2[i];

		for (int i = N - 1; i >= 0; i--) A[--kazu2[tmp[i] >> k * b & ((1 << b) - 1)]] = tmp[i];

	}

}



int main() {

	//cin.tie(0);

	//ios::sync_with_stdio(false);



	int N = getint(), K = getint();

	int saidai[100000] = {};

	int shurui = 0;

	int sonota[100001];

	int k = 0;

	rep(i, N) {

		int t = getint() - 1;

		int d = getint();

		if (!saidai[t]) {

			shurui++;

			saidai[t] = d;

		}

		else {

			if (saidai[t] < d) {

				swap(saidai[t], d);

			}

			sonota[k++] = d;

		}

	}



	pakuri_sort(100000, saidai);

	pakuri_sort(k, sonota);



	ll sonota2[100000];

	sonota2[k - 1] = sonota[k - 1];

	for (int i = k - 1; i >= 1; i--) {

		sonota2[i - 1] = sonota2[i] + sonota[i - 1];

	}



	ll kari = 0;

	ll kotae = 0;

	for (int i = 1; i <= min(K, shurui); i++) {

		kari += saidai[100000 - i];

		ll kari2 = kari;

		if (K - i > 0 && 0 <= k - K + i) kari2 += sonota2[k - K + i];

		kari2 += 1ll * i * i;

		kotae = max(kotae, kari2);

	}



	printf("%lld", kotae);



	Would you please return 0;

}

// Fastest known solution for this problem: