/*
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*/
#include<bits/stdc++.h>
using namespace std;
#define ALL(obj) (obj).begin(), (obj).end()
#define REP(i, n) for(int i = 0;i < (n);++i)

#define endl '\n'
#define pb push_back
#define mkp make_pair
#define p_q priority_queue
#define MOD 1000000007LL
#define INF 2000000000
#define PI 3.1415926

const int dx[]={1,0,-1,0}, dy[]={0,-1,0,1};
const int dx_8[]={1,1,0,-1,-1,-1,0,1}, dy_8[]={0,-1,-1,-1,0,1,1,1};

// typedef long long ll;
#define int long long

template <typename T> inline T GCD(T a,T b){T c;while(b!=0){c=a%b;a=b;b=c;}return a;}
template <typename T> inline T LCM(T a,T b){T c=GCD(a,b);a/=c;return a*b;}
template <typename T> inline T nCr(T a,T b){T i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
template <typename T> inline T nHr(T a,T b){return nCr(a+b-1,b);}

signed main(void){
	cin.tie(0);
	ios::sync_with_stdio(false);

	int n, k, t[100000], d[100000]; cin >> n >> k;
	vector<pair<int, int> > vec;
	REP(i, n){
		cin >> t[i] >> d[i];
		vec.pb(mkp(d[i], t[i]));
	}
	sort(ALL(vec)); reverse(ALL(vec));

	int num = 0, type = 0; map<int, int> mp; vector<int> p;
	REP(i, k){
		num += vec[i].first;
    if(mp.count(vec[i].second) == 0){
      type++;
      mp[vec[i].second] = 1;
    }
    else p.pb(vec[i].first);
	}
	int ans = num + type*type;
	cerr << ans << endl;

  for(int i = k; i < n; i++){
    if(mp.count(vec[i].second) != 0) continue;
    if(p.size() == 0) break;

    num -= p.back(); p.pop_back();
    num += vec[i].first;
    mp[vec[i].second] = 1;
    type++;

    ans = max(ans, num+type*type);
  }
  cout << ans << endl;

  return 0;
}

Measured memory_bytes: 7664