/*************************************
* author: marvinthang *
* created: 15.05.2023 18:35:26 *
*************************************/
#include "aliens.h"
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define left ___left
#define right ___right
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define MASK(i) (1LL << (i))
#define BIT(x, i) ((x) >> (i) & 1)
#define __builtin_popcount __builtin_popcountll
#define ALL(v) (v).begin(), (v).end()
#define REP(i, n) for (int i = 0, _n = (n); i < _n; ++i)
#define REPD(i, n) for (int i = (n); i--; )
#define FOR(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define FORD(i, b, a) for (int i = (b), _a = (a); --i >= _a; )
#define FORE(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORDE(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define scan_op(...) istream & operator >> (istream &in, __VA_ARGS__ &u)
#define print_op(...) ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
#include "debug.h"
#else
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define DB(...) 23
#define db(...) 23
#define debug(...) 23
#endif
template <class U, class V> scan_op(pair <U, V>) { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>) { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>) { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")"; else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
template <class A, class B> bool minimize(A &a, B b) { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b) { if (a < b) { a = b; return true; } return false; }
// end of template
const long long INF = 1e18;
const int MAX = 5005;
long long sqr(int a) {
return 1LL * a * a;
}
int dp[MAX][MAX], opt[MAX][MAX];
vector <pair <int, int>> squares;
int cost(int i, int j) {
int cur_r = i ? squares[i - 1].se : 0;
int new_l = squares[i].fi;
int new_r = squares[j].se;
int c = sqr(new_r - new_l + 1);
if (new_l <= cur_r) c -= sqr(cur_r - new_l + 1);
return c;
}
long long take_photos(int N, int m, int K, vector <int> X, vector <int> Y) {
vector <pair <int, int>> squares;
vector <int> ma(m + 1);
REP(i, N) {
++X[i]; ++Y[i];
if (X[i] > Y[i]) swap(X[i], Y[i]);
maximize(ma[X[i]], Y[i]);
}
int cur = 0;
FORE(i, 1, m) {
if (ma[i] > cur) squares.push_back(make_pair(i, ma[i]));
cur = max(cur, ma[i]);
}
memset(dp, 0x3f, sizeof(dp));
dp[0][0] = 0;
N = squares.size();
K = min(N, K);
FORE(k, 1, K) FORDE(i, N, 1)
FOR(j, opt[i][k - 1], i == N ? N - 1 : opt[i + 1][k])
if (minimize(dp[i][k], dp[j][k - 1] + cost(j, i - 1))) opt[i][k] = j;
return dp[N][K];
}
#ifdef LOCAL
#include "aliens.h"
#include <cstdio>
#include <cassert>
int main() {
file("aliens");
int n, m, k;
assert(3 == scanf("%d %d %d", &n, &m, &k));
std::vector<int> r(n), c(n);
for (int i = 0; i < n; i++) {
assert(2 == scanf("%d %d", &r[i], &c[i]));
}
long long ans = take_photos(n, m, k, r, c);
printf("%lld\n", ans);
return 0;
}
#endif
