#include<vector>
#include<iostream>
#include <stdlib.h>
#include <algorithm>
#include <stack>
using namespace std;
int N;
int main(){
cin >> N;
vector<int> a(N), b(N);
for (int i=0;i<N;i++)
cin >> a[i] >> b[i];
int cost = 0;
stack<pair<int,int>> left;
stack<pair<int,int>> right;
for (int i=N-1;i>0;i--){
if (a[i] > b[i]) right.push({a[i] - b[i], i});
}
for (int i=0;i<N;i++){
while (!right.empty() && right.top().second <= i) right.pop();
if (a[i] == b[i]) continue;
if (a[i] > b[i]) left.push({a[i] - b[i], i}); else {
int deficit = b[i] - a[i];
while (deficit > 0){
if (left.empty()) {
cost += abs(right.top().second - i) * min(deficit, right.top().first);
if (deficit >= right.top().first){
deficit -= right.top().first;
right.pop();
} else {
right.top().second -= deficit;
deficit = 0;
}
} else if (right.empty()){
cost += abs(left.top().second - i) * min(deficit, left.top().first);
if (deficit >= left.top().first){
deficit -= left.top().first;
left.pop();
} else {
left.top().second -= deficit;
deficit = 0;
}
} else if (abs(left.top().second - i) > abs(right.top().second - i)) {
cost += abs(right.top().second - i) * min(deficit, right.top().first);
if (deficit >= right.top().first){
deficit -= right.top().first;
right.pop();
} else {
right.top().second -= deficit;
deficit = 0;
}
} else {
cost += abs(left.top().second - i) * min(deficit, left.top().first);
if (deficit >= left.top().first){
deficit -= left.top().first;
left.pop();
} else {
left.top().second -= deficit;
deficit = 0;
}
}
}
}
}
cout << cost << endl;
return 0;
}
