#include<iostream>
#include<string>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<vector>
#include<list>
#include<cstdint>
#include<bits/stdc++.h>
#include<queue>
#include<set>

#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rep_r(i, n) for(int i = n-1; i >= 0; i--)
#define rep1(i, n) for(int i = 1; i <= (int)(n); i++)
#define REP(i,n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((ll)(x).size())
#define bit(n) (1LL<<(n))
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );

#define INF bit(60)
#define pb push_back
#define mod 1000000007

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

using namespace std;
using uif=uint_fast64_t;
using ll=long long int;

int qp(int a,ll b){int ans=1;do{if(b&1)ans=1ll*ans*a%mod;a=1ll*a*a%mod;}while(b>>=1);return ans;}
int qp(int a,ll b,int mo){int ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}

int gcd(int a,int b){return b?gcd(b,a%b):a;}
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};


#define FACSIZE 2002

ll invfac[FACSIZE];
ll fac[FACSIZE];

ll mod_pow(ll ,ll );
ll mod_add(ll ,ll );
ll mod_mul(ll ,ll );
ll mod_div(ll ,ll );
void make_fact(ll );
void make_invfact(ll );



int main(void){
  ll ans=0;
  
  using pa=pair<ll,ll>;

  ll n,k;
  cin>>n>>k;
  vector<ll> t(n);
  vector<ll> d(n);

  priority_queue< pa > pq;
  priority_queue< pa,vector<pa>,greater<pa> > pq_remove_cand;

  rep(i,n){
    cin>>t[i]>>d[i];
    pq.push(make_pair(d[i],t[i]));
    
  }

  unordered_map<ll,ll> um;
  unordered_map<ll,ll> um_kind;
  ll score=0;
  ll kind=0;
  ll score_base=0;
  rep(i,k){
    auto q=pq.top();
    //cout << q.first << "," << q.second << endl;
    pq.pop();
    pq_remove_cand.push(q);
    score_base+=q.first;
    um[q.second]++;
  }
  kind=um.size();
  //cout << "kind:" << kind << endl;
  score=score_base+kind*kind;
  ans=max(ans,score);
  //cout << "ans:" << ans << endl;
  while(!pq.empty()){

    auto q=pq.top();
    pq.pop();
    if( um.find(q.second) != end(um) ) continue;
    else{
      //cout << "In:" << q.first << "," << q.second << endl;
      pq_remove_cand.push(q);
      um[q.second]++;
      while( !pq_remove_cand.empty() ){
        auto cq=pq_remove_cand.top();
        pq_remove_cand.pop();
        if( um[cq.second]>1 ){
          //cout << "Out:" << cq.first << "," << cq.second << endl;
          um[cq.second]--;
          score = score + (kind+1)*(kind+1)-kind*kind + q.first - cq.first ;
          ans=max(ans,score);
          //cout << "ans:" << ans << endl;
          kind++;
          //cout << "kind:" << kind << endl;
          break;
        }
      }
    }

  }

  cout << ans << endl;

  return 0;

}

ll mod_pow(ll x,ll r){
  if(r==0) return 1;
  else if(r==1) return x%mod;
  else if(r%2==0){
    ll t=mod_pow(x,r/2)%mod;
    return t*t %mod;
  } 
  else{
    ll t=mod_pow(x,r/2)%mod;
    ll k= t*t %mod;
    return k*x%mod;
  } 
}
ll mod_add(ll a,ll b){
  return (a+b)%mod;
}

ll mod_mul(ll a,ll b){
  return (a*b)%mod;
}

ll mod_div(ll a,ll b){
  return mod_mul(a,mod_pow(b,mod-2));
}

void make_fact(ll n){
  fac[0]=1;
  rep(i,n){
    fac[i+1]=mod_mul(fac[i],i+1);
  }  
}

void make_invfact(ll n){
  invfac[n]= mod_pow( fac[n] ,mod-2);
  for(int i=n-1;i>=0;i--){
    invfac[i]=mod_mul(invfac[i+1],i+1);
  }

}


Measured memory_bytes: 8944