#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 5e5 + 5;
int n, a[N], b[N], c[N];
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i] >> b[i];
c[i] = c[i - 1] + a[i] - b[i];
}
int res = 0;
for (int i = 1; i <= n; ++i) {
if (c[i] < 0) {
res += -c[i];
c[i] = 0;
}
if (c[i] > c[n]) {
res += c[i] - c[n];
c[i] = c[n];
}
}
priority_queue <int> pq;
while (!pq.empty()) pq.pop();
for (int i = 1; i <= n; ++i) {
pq.push(c[i]);
if (c[i] < pq.top()) {
res += pq.top() - c[i];
pq.pop();
pq.push(c[i]);
}
}
cout << res << endl;
return 0;
}
