#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define int long long
#define ll long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<char,char> pcc;
typedef pair<int,pii> ipii;
typedef pair<pii,pii> ipiii;
const int MAXN = 1e5+10;
const int MAXA = 1e6;
const int INF = 1e18+10;
const int MOD = 1e9+7;
const int LOG = 32;
const ld EPS = 1e-12;
int n, ans;
set <pii> pq;
signed main(){
// ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n;
vector<pii> vec;
for(int i=1; i<=n; i++){
int x, y; cin>>x>>y; vec.pb({x,y});
}
sort(vec.begin(), vec.end());
pq.insert({MAXN+1, INF});
int las = MAXN+1, p = 0;
for(auto [x,y] : vec){
if(x!=p){
pq.insert(pii(las-(x-p), 0));
las = las-(x-p); p = x;
}
// cout << x << ' '<< y << "xy\n";
// masukin y
vector <pii> te;
int sis = y;
while(sis != 0){
pii sta = *pq.begin();
pq.erase(pq.begin());
pii en = *pq.begin();
if(sis >= en.fi-sta.fi){
ans += (en.fi-sta.fi) * sta.se;
te.pb({sta.fi, sta.se+1});
sis -= en.fi-sta.fi;
} else {
ans += sis * sta.se;
te.pb({sta.fi, sta.se});
te.pb({en.fi-sis, sta.se+1});
sis = 0;
}
}
te.pb(*pq.begin()); pq.erase(pq.begin());
for(auto in : te){
auto it = pq.lower_bound(in);
if(it==pq.begin()) pq.insert(in);
else {
it--;
if((*it).se != in.se) pq.insert(in);
// gk ush masukin kalo sama
}
}
// for(auto [p,q] : pq) cout << p << ' ' << q << " xy\n";
}
cout << ans << '\n';
}
