// #pragma comment(linker, "/stack:200000000")
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4")
// #pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
// #define _GLIBCXX_DEBUG
// #define _GLIBCXX_DEBUG_PEDANTIC
#ifdef LOCAL
#else
#include "aliens.h"
#endif
#include <iomanip>
#include <cassert>
#include <iostream>
#include <vector>
#include <random>
#include <algorithm>
#include <map>
#include <set>
#include <functional>
#include <array>
#include <numeric>
#include <queue>
#include <deque>
#include <bitset>
#include <cmath>
#include <climits>
#include <cstdint>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// #include <ext/rope>
// using namespace __gnu_pbds;
// using namespace __gnu_cxx;
using namespace std;
const int MOD = 998244353;
const long double PI = 3.141592653589793;
using ll = long long;
const ll INF = 1e18;
// #define int ll
// --------> sashko123`s defines:
#define itn int //Vasya sorry :(
#define p_b push_back
#define fi first
#define se second
#define pii std::pair<int, int>
#define oo LLONG_MAX
#define big INT_MAX
#define elif else if
int input()
{
int x;
cin >> x;
return x;
}
// ----------> end of sashko123`s defines (thank you Vasya <3)
// template<typename K, typename V>
// using hash_table = cc_hash_table<K, V, hash<K>>;
// template<typename T>
// using ordered_set = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
template<typename T> struct li_chao_tree {
const T MX = 1e9 + 1;
struct line {
T k = 0;
T b = -INF;
ll lam = 0;
pair<T, T> f(T x) const {
return {k * x + b, lam};
}
};
struct node {
line ln;
int id = 0;
node* left = nullptr;
node* right = nullptr;
};
node* new_node() {
const int N = 100000;
static node* block;
static int count = N;
if (count == N) {
block= new node[N];
count = 0;
}
return (block + count++);
};
node* root = new_node();
pair<T,T> get(T x) {
auto [y, lam] = get(root, -MX, MX, x);
return {-y, -lam};
}
void add(line ln) {
ln.b *= -1;
ln.k *= -1;
ln.lam *= -1;
add(root, -MX, MX, ln);
}
pair<T,T> get(node*& v, T l, T r, T x) {
if (!v || l > r) {
return {-INF, -INF};
}
auto ans = v->ln.f(x);
if (r == l) {
return ans;
}
T mid = (r + l) / 2;
if (x <= mid) {
return max(ans, get(v->left, l, mid, x));
} else {
return max(ans, get(v->right, mid + 1, r, x));
}
}
void add(node*& v, T l, T r, line ln) {
if (l > r)
return;
if (!v) {
v = new_node();
}
T m = (r + l) / 2;
bool left = v->ln.f(l) < ln.f(l);
bool md = v->ln.f(m) < ln.f(m);
if (md)
swap(v->ln, ln);
if (l == r) {
return;
}
if (left != md) {
add(v->left, l, m, ln);
} else {
add(v->right, m + 1, r, ln);
}
}
};
vector<pii> a;
const int N = 600;
const int K = 600;
ll W(ll l, ll r) {
if (r - l >= 0)
return (r - l) * (r - l);
return 0ll;
}
vector<pii> recalc(vector<pii> a, int n) {
sort(a.begin(), a.end(), [&](pii x, pii y) {
return tuple{x.second, -x.first} < tuple{y.second, -y.first};
});
set<pii> st;
for (int i = 0; i < n; i++) {
auto [l, r] = a[i];
while (!st.empty() && st.rbegin()->first >= l) {
st.erase(prev(st.end()));
}
st.insert({l, r});
}
return vector(st.begin(), st.end());
}
pair<ll, ll> check(int n, ll lambda) {
li_chao_tree<ll> ch;
ch.add({.k = -2 * a[1].first, .b = 1ll * a[1].first * a[1].first, .lam = 0});
ll cur = 0, cnt = 0;
for (int i = 1; i <= n; i++) {
auto best = ch.get(a[i].second);
cur = best.first + 1ll * a[i].second * a[i].second + lambda;
cnt = best.second + 1;
if (i + 1 <= n) {
ll k = -2 * a[i + 1].first;
ll b = cur - W(a[i + 1].first, a[i].second) + 1ll * a[i + 1].first * a[i + 1].first;
ch.add({k, b, cnt});
}
}
return {cur, cnt};
}
ll take_photos(int n, int m, int k, vector<int> rr, vector<int> cc) {
a.resize(n);
for (int i = 0; i < n; i++) {
int r = rr[i], c = cc[i];
if (r > c)
swap(r, c);
a[i] = {r, c};
}
a = recalc(a, n);
n = a.size();
for (int i = 0; i < n; i++)
a[i].first--;
a.insert(a.begin(), {0, 0});
if (check(n, 0).second <= k) {
auto [res, cnt] = check(n, 0);
return res;
}
ll l = 0, r = 1e9;
while (r - l > 1) {
auto mid = (r + l) / 2;
if (check(n, mid).second <= k)
r = mid;
else
l = mid;
}
auto [res, cnt] = check(n, r);
return res - r * k;
}
#ifdef LOCAL
int32_t main(int32_t argc, const char * argv[]) {
cin.tie(0);
cout.tie(0);
ios_base::sync_with_stdio(0);
// insert code here...
int n, m, k;
cin >> n >> m >> k;
vector<int> rr(n);
vector<int> cc(n);
for (int i = 0; i < n; i++)
cin >> rr[i] >> cc[i];
cout << take_photos(n, m, k, rr, cc);
return 0;
}
#endif
