//#include "festival.h"
#include<bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC target("avx2")
#define ll long long
#define ld long double
#define pii pair<int,int>
#define pll pair<ll,ll>
#define plx pair<ll,int>
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(),x.end()
#define vi vector<int>
#define vvi vector<vi>
#define ub(x,i) upper_bound(all(x),i)-x.begin()
#define lb(x,i) lower_bound(all(x),i)-x.begin()
#define sz(x) (ll)x.size()
#define cd complex<double>
#define t3 tuple<ll,ll,ll>
using namespace std;
const int mxn=5e5+5;
ll d[mxn],a[mxn],b[mxn];
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
int n;cin>>n;
for(int i=1;i<=n;i++)cin>>a[i]>>b[i],d[i]=d[i-1]+a[i]-b[i];
priority_queue<ll>pq;
ll rs=0;
for(int i=1;i<n;i++){
if(d[i]<0)d[i]=0;
rs+=d[i];pq.push(d[i]);pq.push(d[i]);pq.pop();
}
while(!pq.empty()){
rs-=min(pq.top(),d[n]);pq.pop();
}
cout<<rs;
}
