import java.io.*;
import java.math.BigInteger;
import java.net.Inet4Address;
import java.util.*;
import java.util.concurrent.CompletableFuture;
import java.util.function.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.LongStream;
import java.util.stream.Stream;
import java.util.Map.Entry;

public class Main implements Runnable {
    static final int MOD = (int) 1e9 + 7;
    static final int MI = (int) 1e9;
    static final long ML = (long) 1e18;
    static final Reader in = new Reader();
    static final PrintWriter out = new PrintWriter(System.out);
    StringBuilder answer = new StringBuilder();
    Random random = new Random(751454315315L + System.currentTimeMillis());

    public static void main(String[] args) {
        new Thread(null, new Main(), "persefone", 1 << 28).start();
    }

    @Override
    public void run() {
        solve();
        printf();
        flush();
    }

    void solve() {
        int n = in.nextInt();
        int k = in.nextInt();
        Pair[] pairs = new Pair[n];
        IntStream.iterate(0, i -> i + 1).limit(n).forEach(i -> {
            pairs[i] = new Pair(in.nextInt(), in.nextInt());
        });
        Arrays.sort(pairs, (p1, p2) -> p2.cost - p1.cost);
        Map<Integer, Integer> map = new HashMap<>();
        long cost = 0;
        for (int i = 0; i < k; i++) {
            cost += pairs[i].cost;
            map.put(pairs[i].type, map.getOrDefault(pairs[i].type, 0) + 1);
        }

        int size = map.size();
        IntFunction<Long> special = x -> 1l * x * x;
        long ans = cost + special.apply(size);
        int pos = k - 1;
        for (int i = k; i < n; i++) {
            int count = 0;
            if (!map.containsKey(pairs[i].type)) {
                while (pos >= 0) {
                    count = map.get(pairs[pos].type);
                    if (count > 1) {
                        break;
                    }
                    pos--;
                }
                if (pos < 0) {
                    break;
                }
                size++;
                map.put(pairs[i].type, 1);
                map.put(pairs[pos].type, count - 1);
                cost += - pairs[pos].cost + pairs[i].cost;
                ans = Math.max(ans, cost + special.apply(size));
                pos--;
            }
        }

        printf(ans);

    }

    static class Pair {
        int type, cost;

        public Pair(int type, int cost) {
            this.type = type;
            this.cost = cost;
        }

        @Override
        public String toString() {
            return "Pair{" +
                    "type=" + type +
                    ", cost=" + cost +
                    '}';
        }
    }

    void printf() {
        out.print(answer);
    }

    void close() {
        out.close();
    }

    void flush() {
        out.flush();
    }

    void printf(Stream<?> str) {
        str.forEach(o -> add(o, " "));
        add("\n");
    }


    void printf(Object... obj) {
        printf(false, obj);
    }

    void printfWithDescription(Object... obj) {
        printf(true, obj);
    }


    private void printf(boolean b, Object... obj) {

        if (obj.length > 1) {
            for (int i = 0; i < obj.length; i++) {
                if (b) add(obj[i].getClass().getSimpleName(), " - ");
                if (obj[i] instanceof Collection<?>) {
                    printf((Collection<?>) obj[i]);
                } else if (obj[i] instanceof int[][]) {
                    printf((int[][]) obj[i]);
                } else if (obj[i] instanceof long[][]) {
                    printf((long[][]) obj[i]);
                } else if (obj[i] instanceof double[][]) {
                    printf((double[][]) obj[i]);
                } else printf(obj[i]);
            }
            return;
        }

        if (b) add(obj[0].getClass().getSimpleName(), " - ");
        printf(obj[0]);
    }

    void printf(Object o) {
        if (o instanceof int[])
            printf(Arrays.stream((int[]) o).boxed());
        else if (o instanceof char[])
            printf(new String((char[]) o));
        else if (o instanceof long[])
            printf(Arrays.stream((long[]) o).boxed());
        else if (o instanceof double[])
            printf(Arrays.stream((double[]) o).boxed());
        else if (o instanceof boolean[]) {
            for (boolean b : (boolean[]) o) add(b, " ");
            add("\n");
        } else
            add(o, "\n");
    }

    void printf(int[]... obj) {
        for (int i = 0; i < obj.length; i++) printf(obj[i]);
    }

    void printf(long[]... obj) {
        for (int i = 0; i < obj.length; i++) printf(obj[i]);
    }

    void printf(double[]... obj) {
        for (int i = 0; i < obj.length; i++) printf(obj[i]);
    }

    void printf(boolean[]... obj) {
        for (int i = 0; i < obj.length; i++) printf(obj[i]);
    }

    void printf(Collection<?> col) {
        printf(col.stream());
    }

    <T, K> void add(T t, K k) {
        if (t instanceof Collection<?>) {
            ((Collection<?>) t).forEach(i -> add(i, " "));
        } else if (t instanceof Object[]) {
            Arrays.stream((Object[]) t).forEach(i -> add(i, " "));
        } else
            add(t);
        add(k);
    }


    <T> void add(T t) {
        answer.append(t);
    }

    static class Reader {
        private BufferedReader br;
        private StringTokenizer st;

        Reader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        Reader(String fileName) throws FileNotFoundException {
            br = new BufferedReader(new FileReader(fileName));
        }

        boolean isReady() throws IOException {
            return br.ready();
        }

        String next() {
            try {
                while (st == null || !st.hasMoreTokens()) {
                    st = new StringTokenizer(br.readLine());
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] nextIntArray(int n) {
            int[] arr = new int[n];
            for (int i = 0; i < n; i++)
                arr[i] = nextInt();
            return arr;
        }

        long nextLong() {
            return Long.parseLong(next());
        }

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

        String nextLine() {
            String s = "";
            try {
                s = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return s;
        }
    }
}

Measured memory_bytes: 51796