#include <bits/stdc++.h>
using namespace std;
#define N 200000
namespace kactl {
typedef long long ll;
#define sz(x) int(x.size())
/**
* Author: Lukas Polacek
* Date: 2009-10-30
* License: CC0
* Source: folklore/TopCoder
* Description: Computes partial sums a[0] + a[1] + ... + a[pos - 1], and
* updates single elements a[i], taking the difference between the old and new
* value. Time: Both operations are $O(\log N)$. Status: Stress-tested
*/
struct FT {
vector<ll> s;
vector<int> k;
void init(int n) {
s.assign(n, 0);
k.assign(n, 0);
}
void update(int pos, ll dif, int c) { // a[pos] += dif
for (; pos < sz(s); pos |= pos + 1) {
s[pos] += dif;
k[pos] += c;
}
}
ll query(int pos) { // sum of values in [0, pos)
ll res = 0;
for (; pos > 0; pos &= pos - 1) res += s[pos - 1];
return res;
}
int lower_bound(int c) { // min pos st sum of [0, pos] >= sum
// Returns n if no sum is >= sum, or -1 if empty sum is.
if (c <= 0) return -1;
int pos = 0; // ll sum = 0;
for (int pw = 1 << 25; pw; pw >>= 1) {
if (pos + pw <= sz(k) && k[pos + pw - 1] < c) {
pos += pw, c -= k[pos - 1];
}
}
return pos;
}
ll q_(int c) { return query(lower_bound(c) + 1); }
} ft;
} // namespace kactl
array<int, 2> aa[N];
int ii[N];
int l_ = 0, r_ = -1, m_;
long long query(int l, int r) {
if (r - l + 1 < m_) return -0x3f3f3f3f3f3f3f3f;
while (l_ < l) kactl::ft.update(ii[l_], -aa[l_][1], -1), l_++;
while (l_ > l) l_--, kactl::ft.update(ii[l_], +aa[l_][1], +1);
while (r_ > r) kactl::ft.update(ii[r_], -aa[r_][1], -1), r_--;
while (r_ < r) r_++, kactl::ft.update(ii[r_], +aa[r_][1], +1);
return kactl::ft.q_(m_) - (long long)2 * (aa[r][0] - aa[l][0]);
}
long long ans = -0x3f3f3f3f3f3f3f3f;
void dnc(int lo, int ro, int l, int r) {
long long tmp;
int m, mo;
if (l > r) return;
m = (l + r) / 2, mo = lo;
tmp = query(mo, m);
for (int i = lo; i <= ro; i++) {
long long tmp_ = query(i, m);
if (tmp_ > tmp) {
tmp = tmp_;
mo = i;
}
}
ans = max(ans, tmp);
if (mo == -1) {
assert(0);
dnc(lo, ro, m + 1, r);
} else {
dnc(lo, mo, l, m - 1);
dnc(mo, ro, m + 1, r);
}
}
int main() {
static int ii_[N];
int n;
scanf("%d%d", &n, &m_);
for (int i = 0; i < n; i++) {
scanf("%d%d", &aa[i][1], &aa[i][0]);
ii_[i] = i;
}
sort(aa, aa + n);
sort(ii_, ii_ + n, [&](int i, int j) { return aa[i][1] > aa[j][1]; });
for (int i = 0; i < n; i++) ii[ii_[i]] = i;
kactl::ft.init(n + 5);
dnc(0, n - 1, 0, n - 1);
printf("%lld\n", ans);
return 0;
}
