#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, m, n) for (int i = m; i < n; ++i)

ll solve() {
  int N, K;
  cin >> N >> K;
  using P = pair<int, int>;
  priority_queue<P> pq; // dec
  rep(i, 0, N) {
    int t, d;
    cin >> t >> d;
    pq.push(P(d, t));
  }
  ll sum = 0;
  map<int, int> ma;
  priority_queue<P,vector<P>,greater<P>> pq2; // inc
  rep(i, 0, K) {
    P t = pq.top(); pq.pop();
    sum += t.first;
    ma[t.second]++;
    pq2.push(t);
  }
  ll n = ma.size();
  ll ans = sum + n * n;
  while(!pq.empty()) {
    P t = pq.top(); pq.pop(); // 追加したい
    if(ma[t.second]) continue;
    while(!pq2.empty() && ma[pq2.top().second] <= 1) pq2.pop();
    if(pq2.empty()) break;
    P s = pq2.top(); pq2.pop(); // 取り除きたい
    pq2.push(t);
    n++;
    sum += t.first;
    sum -= s.first;
    ma[t.second]++;
    ma[s.second]--;
    ans = max(ans, sum + n * n);
  }
  return ans;
}

int main() {
  cout << solve() << endl;
  return 0;
}
