import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.net.ConnectException;
import java.rmi.dgc.Lease;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Set;
import java.util.Stack;
import java.util.TreeMap;
import java.util.TreeSet;

import static java.util.Comparator.*;

public class Main {
	public static void main(String[] args) {
		Main main = new Main();
		main.solve();
		main.out.close();
	}

	// ======================================================================
	// ABC 116 D - Various Sushi
	//
	List<PP> list = new ArrayList<>();				// 全ての寿司
	List<PP> list2 = new ArrayList<>();				// 合計に入っている寿司
	Deque<Integer> DQ = new ArrayDeque<Integer>();	// 合計に入っていない寿司で一番のおいしさ
	Map<Integer, Integer> map = new HashMap<>();	// 合計に入っている種類の数
	Set<Integer> set = new HashSet<>();
	public void solve() {
		int N = ni();
		int K = ni();
		int t, d;
		for (int i = 0; i < N; i++) {
			t = ni();
			d = ni();
			list.add(new PP(t, d));
		}
		list.sort(comparing(PP::getVal, reverseOrder()));
		int cnt = 0;
		long ans = 0;
		for(PP pp : list) {
			if(cnt < K) {
				list2.add(pp);
				ans += pp.val;
				map.merge(pp.key, 1, Integer::sum);
				cnt++;
			} else {
				if(!map.containsKey(pp.key)
						&& !set.contains(pp.key)) {
					set.add(pp.key);
					DQ.offerLast(pp.val);
				}
			}
		}
		long kcnt = map.size();
		ans += (kcnt*kcnt);
		long calc = ans;
		list2.sort(comparing(PP::getVal));
		for(PP pp : list2) {
			if(map.get(pp.key) <= 1)	continue;
			if(DQ.isEmpty())			break;
			calc = calc - pp.val - kcnt * kcnt;
			kcnt++;
			calc = calc + DQ.pollFirst() + kcnt * kcnt;
			ans = Math.max(ans, calc);
		}
		out.println(ans);
	}
	// Set に入れるなら　PPKEY　を使う！
	class PP {
		public int key, val;

		public PP(int key, int val) {
			this.key = key;
			this.val = val;
		}

		public int getKey() {
			return key;
		}

		public void setKey(int key) {
			this.key = key;
		}

		public int getVal() {
			return val;
		}

		public void setVal(int val) {
			this.val = val;
		}
	}
	
	// ------------------------------------------
	// ライブラリ
	// ------------------------------------------
	// Print
	private PrintWriter out = new PrintWriter(System.out);

	// Scanner
	private FastScanner scan = new FastScanner();

	int ni() {
		return scan.nextInt();
	}

	int[] ni(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = ni();
		}
		return a;
	}

	int[][] ni(int y, int x) {
		int[][] a = new int[y][x];
		for (int i = 0; i < y; i++) {
			for (int j = 0; j < x; j++) {
				a[i][j] = ni();
			}
		}
		return a;
	}

	long nl() {
		return scan.nextLong();
	}

	long[] nl(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++) {
			a[i] = nl();
		}
		return a;
	}

	long[][] nl(int y, int x) {
		long[][] a = new long[y][x];
		for (int i = 0; i < y; i++) {
			for (int j = 0; j < x; j++) {
				a[i][j] = nl();
			}
		}
		return a;
	}

	String ns() {
		return scan.next();
	}

	String[] ns(int n) {
		String[] a = new String[n];
		for (int i = 0; i < n; i++) {
			a[i] = ns();
		}
		return a;
	}

	String[][] ns(int y, int x) {
		String[][] a = new String[y][x];
		for (int i = 0; i < y; i++) {
			for (int j = 0; j < x; j++) {
				a[i][j] = ns();
			}
		}
		return a;
	}
}

class FastScanner {
	private final InputStream in = System.in;
	private final byte[] buffer = new byte[1024];
	private int ptr = 0;
	private int buflen = 0;

	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		} else {
			ptr = 0;
			try {
				buflen = in.read(buffer);
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen <= 0) {
				return false;
			}
		}
		return true;
	}

	private int readByte() {
		if (hasNextByte())
			return buffer[ptr++];
		else
			return -1;
	}

	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}

	public boolean hasNext() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
		return hasNextByte();
	}

	public String next() {
		if (!hasNext())
			throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while (isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	public long nextLong() {
		if (!hasNext())
			throw new NoSuchElementException();
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while (true) {
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			} else if (b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			} else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}

	public int nextInt() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
			throw new NumberFormatException();
		return (int) nl;
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}
}


Measured memory_bytes: 67504