#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
#define maxs(x,y) (x = max(x,y))
#define mins(x,y) (x = min(x,y))
#define limit(x,l,r) max(l,min(x,r))
#define lims(x,l,r) (x = max(l,min(x,r)))
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)),x.end())
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define show(x) cout<<#x<<" = "<<x<<endl;
#define PQ(T) priority_queue<T,v(T),greater<T> >
#define bn(x) ((1<<x)-1)
#define dup(x,y) (((x)+(y)-1)/(y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
inline int in() { int x; scanf("%d",&x); return x;}
template<typename T>inline istream& operator>>(istream&i,v(T)&v)
{rep(j,sz(v))i>>v[j];return i;}
template<typename T>string join(const v(T)&v)
{stringstream s;rep(i,sz(v))s<<' '<<v[i];return s.str().substr(1);}
template<typename T>inline ostream& operator<<(ostream&o,const v(T)&v)
{if(sz(v))o<<join(v);return o;}
template<typename T1,typename T2>inline istream& operator>>(istream&i,pair<T1,T2>&v)
{return i>>v.fi>>v.se;}
template<typename T1,typename T2>inline ostream& operator<<(ostream&o,const pair<T1,T2>&v)
{return o<<v.fi<<","<<v.se;}
template<typename T>inline ll suma(const v(T)& a) { ll res(0); for (auto&& x : a) res += x; return res;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#define dame { puts("-1"); return 0;}
#define yn {puts("Yes");}else{puts("No");}
const int MX = 200005;

    // 整数スキャン（複数）
    /*
    int x;
    scanf("%d",&x);
    int y;
    scanf("%d",&y);
    int z;
    scanf("%d",&z);

    // n個の整数のスキャン
    /*
    ll a[n] = {};
    rep(i,n){
        scanf("%lld",&a[i]);
    }
    */

    // 文字列スキャン
    /*
    string s;
    cin >> s;
    */

    // n個の文字列スキャン
    /*
    vector<string> slist;
    rep(i,n){
        string s;
        cin >> s;
        slist.push_back(s);
    }
    */

int main() {
    ll n,k;
    scanf("%lld%lld",&n,&k);
    vector<pair<ll, ll> > p(n);
    rep(i,n){
        ll t,d;
        scanf("%lld%lld",&t,&d);
        p[i] = make_pair(d, t);
    }
    sort(p.begin(), p.end());
    /*
    rep(i,n){
        printf("(%d,%d) ", p[i].first, p[i].second);
    }
    puts("");
    */
    if(k==1){
        cout << p[n-1].fi+1 << endl;
        return 0;
    }

    ll flag[n+1]={};//flag
    ll syu=0;
    ll ct = 0;
    ll taiki[k+1] = {};
    for(int i=n-1;i>=n-k;i--){
        if(flag[p[i].se]==0){
            flag[p[i].se]++;
            syu++;
        }else{
            taiki[ct]=p[i].fi;
            //cout << taiki[ct];
            ct++;
        }
    }
    ll hoketsu[n+1];
    ll ch = 0;
    for(int i=n-k-1;i>=0;i--){
        if(flag[p[i].se]==0){
            hoketsu[ch]=p[i].fi;
            flag[p[i].se]++;
            ch++;
        }
    }

    ll ans = 0;
    for(int i=n-1;i>=n-k;i--){
        ans+=p[i].fi;
    }
    ans+=syu*syu;
    //cout << ans << endl;

    ll nn = min(ct,ch);
    ll ans2=ans;
    rep(i,nn){
        
        ans2-=syu*syu;
        ans2-=taiki[ct-1-i];
        ans2+=hoketsu[i];
        syu++;
        ans2+=syu*syu;
        //cout << ans2;
        maxs(ans,ans2);
    }

    
    cout << ans << endl;
    return 0;
}
 
 


Measured memory_bytes: 3328