#include <bits/stdc++.h>
using namespace std;
#ifndef LOCAL
#include "aliens.h"
#endif
struct Line {
long long a, b;
double x(const auto& rhs) { return 1.0 * (rhs.b - b) / (a - rhs.a); };
};
long long take_photos(int n, int m, int k, vector<int> r, vector<int> c) {
using pii = pair<int, int>;
vector<pii> p(n);
for (int i = 0; i < n; ++i) {
if (r[i] > c[i]) swap(r[i], c[i]);
p[i] = {r[i], c[i]};
}
auto dis = [&](pii a) { return abs(a.first - a.second) + 1; };
sort(p.begin(), p.end(), [&](const auto& a, const auto& b) {
return make_pair(a.first, -dis(a)) < make_pair(b.first, -dis(b));
});
vector<bool> mk(n, true);
pii point = {-1, -1};
for (int i = 0; i < n; ++i) {
if (point.first <= p[i].first && p[i].second <= point.second) mk[i] = false;
else point = p[i];
}
int cnt = 0;
for (int i = 0; i < n; ++i) {
cnt += mk[i];
if (mk[i]) p.push_back(p[i]);
}
p.erase(p.begin(), p.begin() + n);
p.push_back({-1, -1});
k = min(k, n = cnt);
vector<vector<long long>> f(k + 1, vector<long long>(n + 1, 1e15));
sort(p.begin(), p.end(), [&](const auto& a, const auto& b) { return a.first < b.first; });
f[0][0] = 0;
for (int i = 1; i <= k; ++i) {
vector<Line> hull;
for (int j = 1; j <= n; ++j) {
long long pl = -p[j].first + 1;
long long pre = max(0ll, p[j - 1].second + pl); pre *= pre;
Line line = {2 * pl, f[i - 1][j - 1] + pl * pl - pre};
while (hull.size() > 1 && hull.end()[-2].x(hull.end()[-1]) > hull.end()[-2].x(line))
hull.pop_back();
hull.push_back(line);
auto cal = [&](int it) {
const auto& [a, b] = hull[it];
long long x = p[j].second;
return a * x + b + x * x;
};
int l = 0, r = hull.size() - 2, it = 0;
while (l <= r) {
int mid = l + r >> 1;
if (cal(mid) >= cal(mid + 1)) l = it = mid + 1;
else r = mid - 1;
}
f[i][j] = cal(it);
}
}
return f[k][n];
}
#ifdef LOCAL
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
int n, m, k; cin >> n >> m >> k;
vector<int> r(n), c(n);
for (int i = 0; i < n; ++i) cin >> r[i] >> c[i];
cout << take_photos(n, m, k, r, c) << "\n";
}
#endif
