#include <bits/stdc++.h>
using namespace std;

# define REP(i,n) for (int i=0;i<(n);++i)
# define rep(i,a,b) for(int i=a;i<(b);++i)
# define p(s) std::cout << s ;
# define pl(s)  std::cout << s << endl;
# define printIf(j,s1,s2) cout << (j ? s1 : s2) << endl;
# define YES(j) cout << (j ? "YES" : "NO") << endl;
# define Yes(j) std::cout << (j ? "Yes" : "No") << endl;
# define yes(j) std::cout << (j ? "yes" : "no") << endl;
# define all(v) v.begin(),v.end()
# define showVector(v) REP(i,v.size()){p(v[i]);p(" ")} pl("")
template<class T> inline bool chmin(T &a, T b){ if(a > b) { a = b; return true;} return false;}
template<class T> inline bool chmax(T &a, T b){ if(a < b) { a = b; return true;} return false;}
typedef long long int ll;
typedef pair<ll,ll> P_ii;
typedef pair<double,double> P_dd;

template<class T>
vector<T> make_vec(size_t a){
    return vector<T>(a);
}

template<class T, class... Ts>
auto make_vec(size_t a, Ts... ts){
  return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}

template<typename T,typename V>
typename enable_if<is_class<T>::value==0>::type
fill_v(T &t,const V &v){t=v;}

template<typename T,typename V>
typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t,const V &v){
  for(auto &e:t) fill_v(e,v);
}


const int MOD = 1000000007;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;

void addM(long long &a, long long b) {
    a += b;
    if (a >= MOD) a -= MOD;
}

void mulM(long long &a, long long b) {
    a = ((a%MOD)*(b%MOD))%MOD ;
}

// a^b mod M
long myPow(long a,long b,int M) {
    long ret = 1;
    long tmp = a;
    while(b>0) {
        if((b&1)==1) ret = (ret * tmp) % M;
        tmp = (tmp * tmp) % M;
        b = b>>1;
    }
    return ret;
}

 // nCk mod M
int nCk(int n,int k,int M) {
    long ret = 1;
    int mi = min(k, n-k);
    for(int i=1;i<=mi;i++) {
        ret = (ret * myPow(i,M-2,M)) % M;
    }
    for(int i=n-mi+1;i<=n;i++) {
        ret = (ret * i) % M;
    }
    return (int)ret;
};

int main() {
    int N,K;cin >> N >> K;

    vector<P_ii> s_v(N);
    REP(i,N) cin >> s_v[i].second >> s_v[i].first;
    sort(all(s_v),greater<P_ii>());

    ll ans = 0;
    set<ll> se_ex;
    vector<P_ii> sushi_ex_v;
    REP(i,K) {
        ll d = s_v[i].first;
        ll t = s_v[i].second;
        ans += d;
        if(se_ex.count(t)!=0){
            sushi_ex_v.push_back({d,t});
        }
        se_ex.insert(t);
    }
    ans += se_ex.size()*se_ex.size();
    sort(all(sushi_ex_v));

    set<ll> se_in;
    vector<P_ii> sushi_in_v;
    rep(i,K,N) {
        ll d = s_v[i].first;
        ll t = s_v[i].second;
        if(se_in.count(t)==0 && se_ex.count(t)==0){
            sushi_in_v.push_back({d,t});
        }
        se_in.insert(t);
    }
    sort(all(sushi_in_v),greater<P_ii>());

    ll i = 0;
    ll ini_size = se_ex.size();
    ll t_ans = ans;
    ll res_ans = 0;
    for(auto sushi:sushi_ex_v){
        if(sushi_in_v.size() <= i) break;

        t_ans -= sushi.first;
        t_ans += sushi_in_v[i].first;
        
        t_ans -= (ini_size+i)*(ini_size+i);
        t_ans += (ini_size+i+1)*(ini_size+i+1);

        chmax(res_ans,t_ans);

        i++;
    }

    pl(max(ans,res_ans))

    return 0;
}

Measured memory_bytes: 7284