#![allow(non_snake_case)]
#![allow(dead_code)]
#![allow(unused_macros)]
#![allow(unused_imports)]

use std::str::FromStr;
use std::io::*;
use std::collections::*;
use std::cmp::*;

struct Scanner<I: Iterator<Item = char>> {
    iter: std::iter::Peekable<I>,
}

macro_rules! exit {
    () => {{
        exit!(0)
    }};
    ($code:expr) => {{
        if cfg!(local) {
            writeln!(std::io::stderr(), "===== Terminated =====")
                .expect("failed printing to stderr");
        }
        std::process::exit($code);
    }}
}

impl<I: Iterator<Item = char>> Scanner<I> {
    pub fn new(iter: I) -> Scanner<I> {
        Scanner {
            iter: iter.peekable(),
        }
    }

    pub fn safe_get_token(&mut self) -> Option<String> {
        let token = self.iter
            .by_ref()
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect::<String>();
        if token.is_empty() {
            None
        } else {
            Some(token)
        }
    }

    pub fn token(&mut self) -> String {
        self.safe_get_token().unwrap_or_else(|| exit!())
    }

    pub fn get<T: FromStr>(&mut self) -> T {
        self.token().parse::<T>().unwrap_or_else(|_| exit!())
    }

    pub fn vec<T: FromStr>(&mut self, len: usize) -> Vec<T> {
        (0..len).map(|_| self.get()).collect()
    }

    pub fn mat<T: FromStr>(&mut self, row: usize, col: usize) -> Vec<Vec<T>> {
        (0..row).map(|_| self.vec(col)).collect()
    }

    pub fn char(&mut self) -> char {
        self.iter.next().unwrap_or_else(|| exit!())
    }

    pub fn chars(&mut self) -> Vec<char> {
        self.get::<String>().chars().collect()
    }

    pub fn line(&mut self) -> String {
        if self.peek().is_some() {
            self.iter
                .by_ref()
                .take_while(|&c| !(c == '\n' || c == '\r'))
                .collect::<String>()
        } else {
            exit!();
        }
    }

    pub fn peek(&mut self) -> Option<&char> {
        self.iter.peek()
    }
}

trait Joinable {
    fn join(self, sep: &str) -> String;
}

impl<U: ToString, T: Iterator<Item = U>> Joinable for T {
    fn join(self, sep: &str) -> String {
        self.map(|x| x.to_string()).collect::<Vec<_>>().join(sep)
    }
}

fn main() {
    let cin = stdin();
    let cin = cin.lock();
    let mut sc = Scanner::new(cin.bytes().map(|c| c.unwrap() as char));
    let N: usize = sc.get();
    let K: usize = sc.get();
    let mut sushi = vec![Vec::new(); N];
    for _ in 0..N {
        let t: usize = sc.get();
        let d: usize = sc.get();
        sushi[t-1].push(d);
    }
    for i in 0..N {
        sushi[i].sort_by(|a, b| b.cmp(a));
    }
    sushi.sort_by_key(|i| Reverse(*i.get(0).unwrap_or(&0)));
    let mut sel = Vec::new();
    let mut cand = Vec::new();
    let mut tot = 0;
    let mut x = 0;
    for i in 0..K {
        if let Some(&d) = sushi[i].get(0) {
            sel.push((i, d));
            tot += d;
            x += 1;
        }
    }
    for i in 0..N {
        if sushi[i].is_empty() {
            continue;
        }
        for &d in &sushi[i][1..] {
            cand.push((i, d));
        }
    }
    cand.sort_by_key(|&(_, d) | d);
    let mut sel_s = HashSet::new();
    for _ in 0..K-x {
        if let Some((i, d)) = cand.pop() {
            tot += d;
            sel.push((i, d));
            sel_s.insert(i);
        } else {
            break;
        }
    }
    sel.sort_by_key(|&(_, d) | Reverse(d));
    let mut ans = tot + x * x;
    for _ in 0..K {
        if let (Some((i1, d1)), Some((i2, d2))) = (sel.pop(), cand.pop()) {
            tot -= d1;
            tot += d2;
            if !sel_s.contains(&i1) && i2 != i1 {
                x -= 1;
            }
            ans = max(ans, tot + x * x);
        }
    }
    println!("{}", ans);
}


Measured memory_bytes: 10140