#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define pll pair<ll, ll>
#define x first
#define y second
using namespace std;
typedef long long ll;
typedef long double ld;
typedef __gnu_pbds::tree<ll, __gnu_pbds::null_type, less<ll>, __gnu_pbds::rb_tree_tag, __gnu_pbds::tree_order_statistics_node_update> yree;
const ld inf = 0x3fff3fff3fff3fff;
const ll N = 5e5+18;
ll a[N];
signed main(){
cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(0);
ll n;
cin >> n;
for(ll i = 0;i<n;i++){
ll u, v;
cin >> u >> v;
a[i]=u-v;
if(i) a[i]+=a[i-1];
}
priority_queue<ll> pq;
ll res=0;
for(ll i = 0;i+1<n;i++){
if(a[i]<0) res+=-a[i], a[i]=0;
if(a[i]>a[n-1]) res+=a[i]-a[n-1], a[i]=a[n-1];
pq.push(a[i]);
if(pq.top()>a[i]){
res+=pq.top()-a[i];
pq.pop();
pq.push(a[i]);
}
}
cout<<res;
}
