#include <bits/stdc++.h>
using namespace std;
const int N = 200'000 + 10;
int n, m;
pair<int, int> p[N];
vector<int> rrh;
namespace IT {
int f[N << 2];
long long g[N << 2];
void update(int s, int l, int r, int p, int x) {
if (p < l || p > r) return;
if (l == r) {
f[s] += x;
g[s] += 1ll * rrh[l - 1] * x;
return;
}
int mid = (l + r) >> 1;
if (p <= mid) update(s << 1, l, mid, p, x);
else update(s << 1 | 1, mid + 1, r, p, x);
f[s] = f[s << 1] + f[s << 1 | 1];
g[s] = g[s << 1] + g[s << 1 | 1];
}
long long query(int s, int l, int r, int k) {
if (k <= 0 || !f[s]) return 0;
if (k >= f[s]) return g[s];
if (l == r) return 1ll * rrh[l - 1] * min(f[s], k);
int mid = (l + r) >> 1;
return query(s << 1, l, mid, k - f[s << 1 | 1]) + query(s << 1 | 1, mid + 1, r, k);
}
}
int itL = 1, itR = 0;
void MO(int l, int r) {
while (itR < r) IT::update(1, 1, rrh.size(), p[++itR].first, 1);
while (itL < l) IT::update(1, 1, rrh.size(), p[itL++].first, -1);
while (itR > r) IT::update(1, 1, rrh.size(), p[itR--].first, -1);
while (itL > l) IT::update(1, 1, rrh.size(), p[--itL].first, 1);
}
const long long MAX = 1'000'000'000'000'000;
long long f[N];
void dnc(int l, int r, int lt, int rt) {
int mid = (l + r) >> 1;
auto& ret = f[mid];
ret = -MAX;
int opt = lt;
for (int i = min(mid - 1, rt); i >= lt; --i) {
MO(i + 1, mid - 1);
if (IT::f[1] >= m - 2) {
long long value = IT::query(1, 1, rrh.size(), m - 2);
value += rrh[p[i].first - 1] + rrh[p[mid].first - 1];
value += 2ll * (p[i].second - p[mid].second);
if (ret < value) {
ret = value;
opt = i;
}
}
}
if (l < mid) dnc(l, mid - 1, lt, opt);
if (mid < r) dnc(mid + 1, r, opt, rt);
}
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> m;
for (int i = 1; i <= n; ++i) cin >> p[i].first >> p[i].second;
sort(p + 1, p + n + 1, [](const auto& a, const auto& b) {
return make_pair(a.second, a.first) < make_pair(b.second, b.first);
});
{ // discrete
for (int i = 1; i <= n; ++i) rrh.push_back(p[i].first);
sort(rrh.begin(), rrh.end());
rrh.erase(unique(rrh.begin(), rrh.end()), rrh.end());
for (int i = 1; i <= n; ++i) {
p[i].first = upper_bound(rrh.begin(), rrh.end(), p[i].first) - rrh.begin();
}
}
dnc(1, n, 1, n);
cout << *max_element(f + 1, f + n + 1) << "\n";
}
