#include <bits/stdc++.h>
using namespace std;
inline void setin(string s) {
freopen(s.c_str(), "r", stdin);
}
template <typename T> void Min(T &a, T b) {
a = min(a, b);
}
template <typename T> void Max(T &a, T b) {
a = max(a, b);
}
#define int long long
const int mod = 1e9 + 7;
const int inf = 2e9;
const int N = 1e6 + 15;
int n, a[N], b[N], diff[N], d[N];
priority_queue <int> q;
int ans;
int opt[N];
signed main() {
ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0);
// setin("input.txt");
cin >> n;
for(int i = 1; i <= n; ++i)
cin >> a[i] >> b[i];
for(int i = 1; i <= n; ++i)
diff[i] = a[i] - b[i];
for(int i = 1; i <= n; ++i)
d[i] = d[i-1] + diff[i];
for(int i = 1; i <= n; ++i) {
if(d[i] < 0)
ans += abs(d[i]);
Max(d[i], 0LL);
}
for(int i = 1; i <= n; ++i) {
q.push(d[i]);
q.push(d[i]);
opt[i] = q.top();
q.pop();
}
opt[n] = d[n];
for(int i = n - 1; i; --i) {
Min(opt[i], opt[i + 1]);
ans += abs(opt[i] - d[i]);
}
cout << ans << endl;
return 0;
}
