#include <bits/stdc++.h>
#include "aliens.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
#define sq(a) ((ll)(a) * (a))
#define cost(j, i) (sq(r[i] - l[j + 1] + 1) - sq(max(0, r[j] - l[j + 1] + 1)))
ll take_photos(int n, int m, int K, vector<int> R, vector<int> C) {
vector<ii> tmp;
for(int i = 0; i < n; i++) {
if(R[i] > C[i]) swap(R[i], C[i]);
tmp.emplace_back(C[i], R[i]);
}
sort(tmp.begin(), tmp.end());
tmp.erase(unique(tmp.begin(), tmp.end()), tmp.end());
vector<int> l = {-1}, r = {-1};
for(ii seg : tmp) {
if(seg.first == r.back()) continue;
while(l.size() && seg.second <= l.back() && r.back() <= seg.first)
r.pop_back(), l.pop_back();
l.push_back(seg.second);
r.push_back(seg.first);
}
n = l.size() - 1;
ll dp[K + 1][n + 1];
memset(dp, 63, sizeof dp);
for(int i = 1; i <= n; i++)
dp[1][i] = sq(r[i] - l[1] + 1);
for(int k = 2; k <= K; k++) {
for(int i = 1; i <= n; i++) {
for(int j = 1; j < i; j++) {
dp[k][i] = min(dp[k][i], dp[k - 1][j] + sq(r[i] - l[j + 1] + 1) -
sq(max(0, r[j] - l[j + 1] + 1)) );
}
}
}
ll ret = 1e18;
for(int i = 1; i <= K; i++) ret = min(ret, dp[i][n]);
return ret;
}
#ifdef LOCAL_TESTING
int main() {
freopen("in", "r", stdin);
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]));
}
ll ans = take_photos(n, m, k, r, c);
printf("%lld\n", ans);
return 0;
}
#endif
