#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template<typename T>
bool maximize(T& a, const T& b){
if(a < b) return a = b, true;
return false;
}
const int MAX = 2e5 + 5;
const ll inf = 2e18;
int N, K, M;
ll ans;
vector<int> v;
struct cake{
ll V, C;
cake() : V(0), C(0) {}
cake(int V, int C) : V(V), C(C) {}
bool operator < (const cake& o){
return make_pair(C, -V) < make_pair(o.C, -o.V);
}
friend istream& operator >> (istream& in, cake& c){
return in >> c.V >> c.C;
}
} cakes[MAX];
struct segment_tree{
vector<ll> st;
vector<int> cnt;
segment_tree(int n) : st(n << 2), cnt(n << 2) {}
void update(int id, int l, int r, int pos, int delta){
if(l == r){
cnt[id] += delta;
st[id] += delta * v[l];
} else{
int mid = l + r >> 1;
if(pos <= mid) update(id << 1, l, mid, pos, delta);
else update(id << 1 | 1, mid + 1, r, pos, delta);
st[id] = st[id << 1] + st[id << 1 | 1];
cnt[id] = cnt[id << 1] + cnt[id << 1 | 1];
}
}
ll walk(int id, int l, int r, int kth){
if(cnt[id] < kth) return -inf;
if(l == r){
assert(cnt[id] >= kth);
return 1LL * kth * v[l];
} else{
int mid = l + r >> 1;
if(cnt[id << 1 | 1] < kth) return st[id << 1 | 1] + walk(id << 1, l, mid, kth - cnt[id << 1 | 1]);
else return walk(id << 1 | 1, mid + 1, r, kth);
}
}
};
segment_tree tr(0);
int lt, rt;
void shift(int l, int r){
while(rt < r) tr.update(1, 0, M - 1, cakes[++rt].V, +1);
while(l < lt) tr.update(1, 0, M - 1, cakes[--lt].V, +1);
while(r < rt) tr.update(1, 0, M - 1, cakes[rt--].V, -1);
while(lt < l) tr.update(1, 0, M - 1, cakes[lt++].V, -1);
}
ll cost(int l, int r){
shift(l, r);
return tr.walk(1, 0, M - 1, K) - 2 * (cakes[r].C - cakes[l].C);
}
void solve(int l, int r, int optl, int optr){
if(l > r) return;
int m = l + r >> 1, optm = optl;
ll result = -inf;
for(int i = max(m + K - 1, optl); i <= optr; ++i){
if(maximize(result, cost(m, i))){
optm = i;
}
}
// cout << m << " : " << optm << '\n';
ans = max(ans, result);
if(m < r) solve(m + 1, r, optm, optr);
if(l < m) solve(l, m - 1, optl, optm);
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
freopen("task.inp", "r", stdin);
freopen("task.out", "w", stdout);
#endif // LOCAL
cin >> N >> K;
for(int i = 1; i <= N; ++i){
cin >> cakes[i];
}
sort(cakes + 1, cakes + 1 + N);
for(int i = 1; i <= N; ++i) v.push_back(cakes[i].V);
sort(v.begin(), v.end());
v.erase(unique(v.begin(), v.end()), v.end());
for(int i = 1; i <= N; ++i) cakes[i].V = lower_bound(v.begin(), v.end(), cakes[i].V) - v.begin();
M = (int)v.size();
tr = segment_tree(M);
ans = -inf;
lt = 1, rt = 0;
solve(1, N - K + 1, K, N);
cout << ans << '\n';
return 0;
}
