#include<bits/stdc++.h>
#define ll long long
using namespace std;
ll a[100005];
int main(){
priority_queue<ll> q;
ll n;
cin>>n;
a[0]=0;
for(ll i=1;i<=n;i++){
cin>>a[i];
ll x;
cin>>x;
a[i]-=x;
a[i]+=a[i-1];
}
ll ans=0;
for(ll i=1;i<=n;i++){
q.push(0);
q.push(0);
}
ll pos;
for(ll i=1;i<n;i++){
q.push(a[i]);
q.push(a[i]);
ll mx=q.top();
q.pop();
ans+=mx-a[i];
pos=mx;
}
ll k=0,b=ans;
while(q.top()>a[n]){
ll np=q.top();
ll k2=k,b2=0;
while(q.top()==np){
q.pop();
k2--;
}
b2=k*np+b-k2*np;
k=k2;
b=b2;
}
cout<<k*a[n]+b;
}
