#include "bits/stdc++.h"
using namespace std;
typedef pair <int, int> pii;
pii a[200010];
int n, m;
int opt[200010];
const long long inf = 1e18;
long long query(int i, int j) {
vector <int> v;
long long ans = -2 * (a[j].first - a[i].first);
for(int x = i; x <= j; x++) {
v.push_back(a[x].second);
}
sort(v.begin(), v.end(), greater <int> ());
for(int i = 0; i < m; i++) {
ans += v[i];
}
return ans;
}
int search(int b, int e, int p, int q) {
if(b > e) return n+1;
if(b == e) {
return query(p, b) <= query(q, b) ? b : n+1;
}
int mid = (b + e) >> 1;
if(query(p, mid) <= query(q, mid)) {
return search(b, mid, p, q);
} else {
return search(mid + 1, e, p, q);
}
}
int main(int argc, char const *argv[])
{
scanf("%d %d", &n, &m);
for(int i = 1; i <= n; i++) {
int p, q;
scanf("%d %d", &p, &q);
a[i] = pii(q, p);
}
sort(a + 1, a + n + 1);
long long ans = LLONG_MIN;
vector <pii> v;
v.emplace_back(m, 1);
int l = 0;
for(int i = 2; i <= n; i++) {
while(l + 1 < v.size() && v[l + 1].first <= i) {
++l;
}
opt[i] = v[l].second;
while(!v.empty() && i + m - 1 <= v.back().first && query(i, v.back().first) >= query(v.back().second, v.back().first)) {
v.pop_back();
}
int change = search(max(i + m - 1, v.back().first), n, v.back().second, i);
// cout << change << endl;
if(change <= n) {
v.emplace_back(change, i);
}
}
for(int i = m; i <= n; i++) {
// cout << opt[i] << ' ' << i << endl;
ans = max(ans, query(opt[i], i));
}
printf("%lld\n", ans);
return 0;
}
