#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = LLONG_MAX;
// Segment tree to support: find position with minimal value, and increment at position
struct SegTree {
int n;
vector<pair<ll,int>> st; // {value, index}
SegTree(int _n): n(_n) {
st.assign(4*n, {0, 0});
build(1, 1, n);
}
void build(int p, int l, int r) {
if (l == r) {
st[p] = {0, l};
return;
}
int m = (l + r) >> 1;
build(p<<1, l, m);
build(p<<1|1, m+1, r);
st[p] = min(st[p<<1], st[p<<1|1]);
}
// increment value at position idx by 1
void update(int p, int l, int r, int idx) {
if (l == r) {
st[p].first += 1;
return;
}
int m = (l + r) >> 1;
if (idx <= m) update(p<<1, l, m, idx);
else update(p<<1|1, m+1, r, idx);
st[p] = min(st[p<<1], st[p<<1|1]);
}
// get global minimum {value, index}
pair<ll,int> query_min() const {
return st[1];
}
};
int main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
int N;
cin >> N;
vector<pair<int,int>> masts(N);
int maxH = 0;
for(int i = 0; i < N; i++){
cin >> masts[i].first >> masts[i].second; // H, K
maxH = max(maxH, masts[i].first);
}
sort(masts.begin(), masts.end());
SegTree seg(maxH);
ll totalIneff = 0;
// Process each mast
for(auto &p : masts) {
int H = p.first;
int K = p.second;
for(int i = 0; i < K; i++) {
auto [cnt, lvl] = seg.query_min();
// but ensure lvl <= H
// If lvl > H, search manually among [1..H]
if (lvl > H) {
// perform a custom query on [1..H]
// naive approach: scan tree - but H is large, so we do segment tree recursive
// implement helper to query minimal in [1..H]
// (Define inline below)
function<pair<ll,int>(int,int,int,int,int)> qrange = [&](int p, int l, int r, int i, int j)->pair<ll,int> {
if (r < i || l > j) return {INF, -1};
if (l >= i && r <= j) return seg.st[p];
int m = (l + r) >> 1;
auto left = qrange(p<<1, l, m, i, j);
auto right = qrange(p<<1|1, m+1, r, i, j);
return min(left, right);
};
auto qr = qrange(1, 1, maxH, 1, H);
cnt = qr.first;
lvl = qr.second;
}
totalIneff += cnt;
seg.update(1, 1, maxH, lvl);
}
}
cout << totalIneff << "\n";
return 0;
}
