import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.PriorityQueue;
import java.io.BufferedWriter;
import java.util.Set;
import java.util.InputMismatchException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.AbstractCollection;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author prakharjain
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        DVariousSushi solver = new DVariousSushi();
        solver.solve(1, in, out);
        out.close();
    }

    static class DVariousSushi {
        public void solve(int testNumber, InputReader in, OutputWriter out) {
            int n = in.nextInt();
            int k = in.nextInt();

            List<susshi> susshis = new ArrayList<>();

            Set<Integer> maxt = new HashSet<>();
            for (int i = 0; i < n; i++) {
                int t = in.nextInt();
                int d = in.nextInt();
                susshis.add(new susshi(t, d));
                maxt.add(t);
            }

            int max = maxt.size();

            max = Math.min(max, k);

            susshis.sort((s1, s2) -> s2.d - s1.d);

            Set<Integer> dt = new HashSet<>();

            PriorityQueue<susshi> pq = new PriorityQueue<>((s1, s2) -> s1.d - s2.d);

            long ds = 0;
            for (int i = 0; i < k; i++) {
                susshi cs = susshis.get(i);
                if (dt.contains(cs.t)) {
                    pq.add(cs);
                }
                dt.add(cs.t);
                ds += cs.d;
            }

            long ans = ds + ((long) dt.size() * dt.size());

            for (int i = k; i < n; i++) {
                susshi cs = susshis.get(i);
                if (!dt.contains(cs.t)) {
                    if (!pq.isEmpty()) {
                        susshi pc = pq.poll();

                        dt.add(cs.t);

                        ds -= pc.d;
                        ds += cs.d;
                    }
                }

                ans = Math.max(ans, ds + ((long) dt.size() * dt.size()));
            }

            out.println(ans);
        }

        class susshi {
            int t;
            int d;

            public susshi(int t, int d) {
                this.t = t;
                this.d = d;
            }

        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void close() {
            writer.close();
        }

        public void println(long i) {
            writer.println(i);
        }

    }
}



Measured memory_bytes: 47060