#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
/**const int INF = (int) 1e9;
vector<int> v;
void run(int lvl = 0) {
if (lvl == 4) {
vector<int> cv = v;
sort(cv.begin(), cv.end());
int best = INF;
while (next_permutation(cv.begin(), cv.end())) {
int now = 0;
for (int i = 1; i < (int) cv.size(); i++) {
now += abs(cv[i] - cv[i - 1]);
}
now += abs(cv.back() - cv[0]);
if (now < best) {
best = now;
}
}
cv = v;
sort(cv.begin(), cv.end());
cout << "[";
for (int i = 0; i < (int) v.size(); i++) {
cout << v[i];
if (i < v.size() - 1) {
cout << " ";
}
}
cout << "] ";
cout << " -> ";
while (next_permutation(cv.begin(), cv.end())) {
int now = 0;
for (int i = 1; i < (int) cv.size(); i++) {
now += abs(cv[i] - cv[i - 1]);
}
now += abs(cv.back() - cv[0]);
if (now == best) {
cout << "[";
for (int i = 0; i < (int) cv.size(); i++) {
cout << cv[i];
if (i < cv.size() - 1) {
cout << " ";
}
}
cout << "] sau ";
}
}
cout << "\n";
return;
}
for (int i = 1; i <= 4; i++) {
v.push_back(i);
run(lvl + 1);
v.pop_back();
}
}**/
#define int ll
const int N = (int) 2e5 + 7;
const ll INF = (ll) 1e18;
pair<int, int> a[N];
int n, m;
signed main() {
ios::sync_with_stdio(0); cin.tie(0);
// freopen("input", "r", stdin);
/// run();
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cin >> a[i].first >> a[i].second;
}
sort(a + 1, a + n + 1, [&](pair<int, int> a, pair<int, int> b) {
return a.second < b.second;
});
ll ret = -INF;
for (int i = m; i <= n; i++) {
priority_queue<int> pq;
ll s = 0;
vector<int> v;
for (int j = i - 1; j >= 1; j--) {
if (i - j - 1 >= m - 2) {
v.push_back(a[j].first + s + a[i].first - (2 * a[i].second - 2 * a[j].second));
ret = max(ret, a[j].first + s + a[i].first - (2 * a[i].second - 2 * a[j].second));
}
pq.push(-a[j].first);
s += a[j].first;
if ((int) pq.size() > m - 2) {
s -= -pq.top();
pq.pop();
}
}
/**vector<int> sgn;
for (int j = 1; j < (int) v.size(); j++) {
if (v[j] > v[j - 1]) {
sgn.push_back(-1);
} else {
sgn.push_back(+1);
}
}
int changes = 0;
for (int j = 0; j < (int) sgn.size() - 1; j++) {
changes += (sgn[j] != sgn[j + 1]);
}
assert(changes <= 2);**/
}
cout << ret << "\n";
return 0;
}
