#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>
#include <queue>
#include <stack>
#include <unordered_set>
#include <unordered_map>
#include <numeric>

using namespace std;

typedef long long int ll;
typedef pair<int, int> Pii;

const ll mod = 998244353;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n;
  cin >> n;
  vector<ll> a(n), b(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i] >> b[i];
  }

  ll score = accumulate(b.begin(), b.end(), 0LL);
  ll atk = 0;
  for (int i = 0; i < n; i++) {
    ll score_delta = a[i] * (n - i - 1) - (atk + b[i]);
    if (score_delta > 0) {
      score += score_delta;
      atk += a[i];
    }
  }

  cout << score << endl;

  return 0;
}