import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.InputStream;
import java.io.PrintWriter;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.MathContext;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;
import java.util.Scanner;
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) {
        PrintWriter out = new PrintWriter(System.out);
        Solver solver = new Solver(System.in, out);
        solver.solve();
        out.close();
    }
}
class Solver {
	Scanner sc;
	PrintWriter out;
    public Solver(InputStream in, PrintWriter out) {
    	sc = new Scanner(in);
    	this.out = out;
    }
    // ======================================================================
    List<PP> list = new ArrayList<>();
    int[] C = new int[100001];
    PriorityQueue<PP> PQ = new PriorityQueue<>(comparing(PP::getKey));
    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(d, t));
		}
    	list.sort(comparing(PP::getKey, reverseOrder()).thenComparing(PP::getVal));
    	long total = 0, kind = 0, ans = 0;
    	int cnt = 0;
    	PP wk;
    	LOOP:
    	for (PP p : list) {
//    		out.println("開始　 おいしさ　＝　" + p.key + "  種類　＝　" + p.val); 
			if(cnt < K) {
				total += p.key;
				if(C[p.val] == 0)	kind++;
				C[p.val]++;
				PQ.add(p);
			} else {
//				out.println("  削除対象　おいしさ　＝　" + wk.key 
//							+ "  種類　＝　" + wk.val + "  種類の数　＝　" + C[wk.val]);
				if(C[p.val] == 0) {
					while(true) {
						wk = PQ.poll();
						if(wk == null)	break LOOP;
						if(C[wk.val] > 1)	break;
					}
					total = total - wk.key + p.key;
					kind++;
					C[wk.val]--;
					C[p.val]++;
//					PQ.add(p);
				}
			}
			ans = Math.max(ans, total + kind * kind);
			cnt++;
//			out.println("終了　　合計　＝　" + total + "  種類数　＝　" + kind 
//								+ " 　　→　　点数　＝　" + ans);
    	}
    	out.println(ans);
    }
    // Set に入れるなら　PPKEY　を使う！
    static 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;
		}
    }
    // ------------------------------------------
    // 入力
    // ------------------------------------------
    public int ni() {
    	return sc.nextInt();
    }
    public long nl() {
    	return sc.nextLong();
    }
    public String ns() {
    	return sc.next();
    }
    public char[] nc() {
    	return sc.next().toCharArray();
    }
    public int[] ndi(int N) {
    	int[] ans = new int[N];
    	for (int i = 0; i < N; i++) {
			ans[i] = ni();
		}
    	return ans;
    }
    public long[] ndl(int N) {
    	long[] ans = new long[N];
    	for (int i = 0; i < N; i++) {
			ans[i] = nl();
		}
    	return ans;
    }
    public String[] nds(int N) {
    	String[] ans = new String[N];
    	for (int i = 0; i < N; i++) {
			ans[i] = ns();
		}
    	return ans;
    }
    public char[][] ndc(int N) {
    	char[][] ans = new char[N][];
    	for (int i = 0; i < N; i++) {
			ans[i] = nc();
		}
    	return ans;
    }
    public int[][] nddi(int N, int S) {
    	int[][] ans = new int[N][S];
    	for (int i = 0; i < N; i++) {
			for (int j = 0; j < S; j++) {
				ans[i][j] = ni();
			}
		}
    	return ans;
    }
}


Measured memory_bytes: 99228