#include <bits/stdc++.h>
#define int long long
using namespace std;
const int inf=1e9+7;
void prd(deque<pair<int,int>> d){
while(!d.empty()) cout<<"{"<<d.front().first<<", "<<d.front().second<<"}",d.pop_front();
}
signed main() {
// freopen("input.txt","r",stdin);
int n; cin>>n;
vector<int> a(n+1),b(n+1);
for(int i=1; i<=n; i++){
cin>>a[i]>>b[i];
int m=min(a[i],b[i]);
a[i]-=m,b[i]-=m;
}
deque<pair<int,int>> l,r;
for(int i=1; i<=n; i++)
if(a[i])
r.push_back({i,a[i]});
int ans=0;
for(int i=1; i<=n; i++){
while(!r.empty()){
if(r.front().first<=i)
l.push_back(r.front()),
r.pop_front();
else break;
}
// cout<<"i= "<<i<<'\n';
// cout<<"l: "; prd(l); cout<<'\n';
// cout<<"r: "; prd(r); cout<<'\n';
while(b[i]){
pair<int,int> pl=(l.empty()?make_pair(-inf,-inf):l.back());
pair<int,int> pr=(r.empty()?make_pair(inf,-inf):r.front());
pair<int,int> &p=(abs(pl.first-i)<abs(pr.first-i)?l.back():r.front());
int take=min(p.second,b[i]);
b[i]-=take;
ans+=take*abs(p.first-i);
if(p.second-take==0){
if(abs(pl.first-i)<abs(pr.first-i))
l.pop_back();
else r.pop_front();
} else p.second-=take;
}
}
cout<<ans;
}
