#include<bits/stdc++.h>
#define fi first
#define se second
#define pitem item*
using namespace std;
typedef unsigned long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
const ll M=1e6+10;
const ll N=1e5+10;
const ll SS=1<<20;
const ll INFi=1e9;
const ll INFl=1e12;
struct f{
ll a,b;
ll ind;
ll operator()(ll x){
return a*x+b;
}
};
struct item{
f fun;
item *l,*r;
};
pair<ll,ll> dp[N];
f nullp;
bool cmp(f a,f b,ll p,ll k){
if(a.b==INFl) return 0;
if(b.b==INFl) return 1;
if((a(p)<b(p) and a(k)<b(k)) or (a(p)<=b(p) and a(k)<b(k)) or (a(p)<b(p) and a(k)<=b(k))) return 1;
if(a(p)==b(p) and a(k)==b(k) and dp[a.ind].se<dp[b.ind].se) return 1;
return 0;
}
pitem upd(pitem v,f x,ll p=0,ll k=SS-1){
if(p>k) return nullptr;
if(!v){
v=new item;
v->l=nullptr,v->r=nullptr,v->fun=x;
return v;
}
ll sr=(p+k)>>1;
if(cmp(x,v->fun,p,sr)){
v->r=upd(v->r,v->fun,sr+1,k);
v->fun=x;
}else if(cmp(x,v->fun,sr+1,k)){
v->l=upd(v->l,v->fun,p,sr);
v->fun=x;
}else if(cmp(v->fun,x,p,sr))
v->r=upd(v->r,x,sr+1,k);
else v->l=upd(v->l,x,p,sr);
return v;
}
f Query(pitem v,ll x,ll p=0,ll k=SS-1){
if(!v) return nullp;
f pom;
if(x<=((p+k)>>1)) pom=Query(v->l,x,p,(p+k)>>1);
else pom=Query(v->r,x,((p+k)>>1)+1,k);
if(cmp(v->fun,pom,x,x)) return v->fun;
return pom;
}
void clear(pitem v){
if(!v) return;
clear(v->l),clear(v->r);
delete(v);
}
ll t[N],l,val[N],mini[M],mini2[M],kw[N];
ll res=INFl;
ll wsp(ll i){
if(t[i]-val[i]+1>kw[i]) return INFi;
if(val[i]>t[i]) return 0;
return (ll)(t[i]-val[i]+1)*(ll)(t[i]-val[i]+1);
}
f func(ll i){
ll w=wsp(i);
if(w==INFi) return nullp;
f pom;
pom.a=-2LL*val[i],pom.b=dp[i].fi+(ll)val[i]*(ll)val[i]+1LL-2LL*(ll)val[i]-(ll)w;
pom.ind=i;
return pom;
}
bool check(ll c,ll k){
pitem v=nullptr;
ll mm=INFi;
for(ll i=1;i<=l;i++){
mm=min(mm,mini[t[i]]);
ll pom1=INFl;
f curr=Query(v,t[i]);
if(curr.b!=INFl) pom1=curr((ll)t[i])+(ll)t[i]*(ll)t[i]+2LL*(ll)t[i]+c;
dp[i]={(ll)(t[i]-mm+1)*(ll)(t[i]-mm+1)+c,1};
kw[i]=t[i]-mm+1;
if(dp[i].fi>pom1){
dp[i]={pom1,dp[curr.ind].se+1};
kw[i]=t[i]-val[curr.ind]+1;
}
if(i!=l){
f pom2=func(i);
if(pom2.b!=INFl) v=upd(v,pom2);
}
}
clear(v);
if(dp[l].se<=k){
res=dp[l].fi-(ll)k*c;
return 1;
}
return 0;
}
ll take_photos(int n,int m,int k,vi r,vi c){
nullp.a=INFi,nullp.b=INFl;
for(ll i=1;i<=m;i++) mini[i]=INFi;
for(ll i=1;i<=n;i++){
r[i-1]++,c[i-1]++;
if(r[i-1]>c[i-1]) swap(r[i-1],c[i-1]);
mini[c[i-1]]=min(mini[c[i-1]],(ll)r[i-1]);
}
ll akt=INFi;
for(ll i=m;i>=1;i--){
mini2[i]=akt;
akt=min(akt,mini[i]);
}
for(ll i=1;i<=m;i++) if(mini[i]!=INFi) t[++l]=i,val[l]=mini2[i];
ll pocz=0,kon=1000LL*1000LL*1000LL*1000LL+10LL;
while(pocz<=kon){
ll sr=(pocz+kon)>>1;
if(check(sr,k)) kon=sr-1;
else pocz=sr+1;
}
return res;
}
/*ll main(){
ll n,m,k;
cin>>n>>m>>k;
vi r,c;
for(ll i=1,a,b;i<=n;i++){
cin>>a>>b;
r.push_back(a),c.push_back(b);
}
cout<<take_photos(n,m,k,r,c)<<"\n";
}*/
