#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#define DEBUG(...) debug(#__VA_ARGS__, __VA_ARGS__)
#else
#define DEBUG(...) 6
#endif
template<typename T, typename S> ostream& operator << (ostream &os, const pair<T, S> &p) {return os << "(" << p.first << ", " << p.second << ")";}
template<typename C, typename T = decay<decltype(*begin(declval<C>()))>, typename enable_if<!is_same<C, string>::value>::type* = nullptr>
ostream& operator << (ostream &os, const C &c) {bool f = true; os << "["; for (const auto &x : c) {if (!f) os << ", "; f = false; os << x;} return os << "]";}
template<typename T> void debug(string s, T x) {cerr << s << " = " << x << "\n";}
template<typename T, typename... Args> void debug(string s, T x, Args... args) {for (int i=0, b=0; i<(int)s.size(); i++) if (s[i] == '(' || s[i] == '{') b++; else
if (s[i] == ')' || s[i] == '}') b--; else if (s[i] == ',' && b == 0) {cerr << s.substr(0, i) << " = " << x << " | "; debug(s.substr(s.find_first_not_of(' ', i + 1)), args...); break;}}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
vector<long long> diff(n);
for (int i=0; i<n; i++) {
int a, b;
cin >> a >> b;
diff[i] = a - b + (i > 0 ? diff[i-1] : 0);
}
assert(diff[n-1] >= 0);
long long ret = 0;
priority_queue<long long> pq;
for (int i=0; i<n-1; i++) {
if (diff[i] < 0) {
ret -= diff[i];
diff[i] = 0;
} else if (diff[i] > diff[n-1]) {
ret += diff[i] - diff[n-1];
diff[i] = diff[n-1];
}
pq.push(diff[i]);
pq.push(diff[i]);
ret += pq.top() - diff[i];
pq.pop();
}
cout << ret << "\n";
return 0;
}
