#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define all(a) a.begin(),a.end()
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef unsigned long long ull;
typedef vector<int> vi;
void solve(){
int n; cin >> n;
vector<ll> pref(n+1,0);
priority_queue<ll> pq;
ll ans = 0;
for(int i = 1; i <= n; i++){
int a,b; cin >> a >> b;
pref[i] = a-b + pref[i-1];
}
for(int i = 1; i <= n; i++){
if(pref[i] < 0){
ans += -pref[i];
pq.push(0);
pq.pop();
}else if(pref[i] > pref[n]){
ans += pref[i] - pref[n];
pq.push(pref[n]);
pq.pop();
}else{
pq.push(pref[i]);
if(pq.top() > pref[i]){
ans += pq.top() - pref[i];
pq.pop(); pq.push(pref[i]);
}
}
}
cout << ans;
}
signed main(){
cin.tie(0)->sync_with_stdio(0);
int t = 1;
// cin >> t;
while(t--){solve();}
}
