#include<bits/stdc++.h>
#define f first
#define s second
#define int long long
#define pii pair<int,int>
using namespace std;
const int N = 2e5 + 5, mod = 1e9 + 7; // !
int t, m;
multiset<int> s, s_;
struct _ {
int v, c;
} x[N];
int cur = 0;
bool cmp(_ a, _ b) {
return (a.c < b.c);
}
void add(int id) {
s_.insert(x[id].v);
cur += x[id].v;
if(s_.size() == m + 1) {
s.insert(*s_.begin());
cur -= *s_.begin();
s_.erase(s_.find(*s_.begin()));
}
}
void rem(int id) {
if(s.find(x[id].v) != s.end()) {
s.erase(s.find(x[id].v));
return;
}
assert(s_.find(x[id].v) != s_.end());
s_.erase(s_.find(x[id].v));
cur -= x[id].v;
if(s.size()) {
cur += *--s.end();
s_.insert(*--s.end());
s.erase(s.find(*--s.end()));
}
}
main(){
int n;
cin >> n >> m;
for(int i = 1; i <= n; i++) {
cin >> x[i].v >> x[i].c;
}
sort(x + 1, x + n + 1, cmp);
queue< pair<pii, pii> > st;
st.push({{m, n}, {1, n}});
int L = 0, R = 0, ans = 0;
while(st.size()) {
int l = st.front().f.f, r = st.front().f.s, optl = st.front().s.f, optr = st.front().s.s;
st.pop();
int mid = (l + r) / 2;
if(R > mid) {
cur = 0; L = 0; R = 0;
while(s.size()) s.erase(*s.begin());
while(s_.size()) s_.erase(*s_.begin());
}
// cout << L << " __ _ __" << " " << R << endl;
// optl .. min(mid - m + 1, optr) gvawyobs
while(R < mid) {
++R;
add(R);
}
while(L < min(optr, mid - m + 1)) {
if(L) rem(L);
++L;
}
assert(L == min(optr, mid - m + 1));
assert(R == mid);
int X = cur - (x[mid].c - x[min(optr, mid - m + 1)].c) * 2, opt = min(optr, mid - m + 1);
for(int i = min(optr, mid - m + 1) - 1; i >= optl; i--) {
add(i);
if(cur - (x[mid].c - x[i].c) * 2 > X) opt = i, X = cur - (x[mid].c - x[i].c) * 2;
}
L = optl;
ans = max(ans, X);
if(l < mid) st.push({{l, mid - 1},{optl, opt}});
if(mid < r) st.push({{mid + 1, r}, {opt, optr}});
}
cout << ans;
}
