#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define MOD 998244353
void solve(){
ll n, a, b, p = 0, ans = 0;
cin >> n;
vector<ll> tmp;
for(int i = 0; i < n; i ++){
cin >> a >> b;
p += a - b;
tmp.push_back(p);
}
priority_queue<ll> pq;
for(auto c : tmp){
if(c < 0){
ans += -c;
c = 0;
}
else if(c > p){
ans += c - p;
c = p;
}
pq.push(c);
if(pq.top() > c){
ans += (pq.top() - c);
pq.pop();
}
}
cout << ans << '\n';
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int tests = 1;
// cin >> tests;
for(int i = 1; i <= tests; i ++)
solve();
}
