package chelper;

import java.util.SortedSet;
import java.util.TreeSet;

import io.InputReader;
import io.OutputWriter;
import misc.SimpleSavingChelperSolution;


public class TaskB2 extends SimpleSavingChelperSolution {

  public void solve(int testNumber, InputReader in, OutputWriter out) {
    wrapSolve(testNumber, in, out);
  }

  @Override
  public void solve(int testNumber) {
    int l = in.nextInt();
    SortedSet<Pair> team = new TreeSet<>();
    for (int i = 0; i < l; i++) {
      long count = in.nextLong();
      int exp = in.nextInt();
      team.add(new Pair(count, exp));
    }
    long leftovers = 0;
    for (Pair manager : team) {
      long capacity = manager.count * manager.experience;

      long canAttach = Math.min(leftovers, capacity);

      leftovers = manager.count + leftovers - canAttach;
    }

    int maxExp = team.last().experience;

    out.println(Math.max(leftovers, maxExp + 1));
  }

  class Pair implements Comparable<Pair> {
    long count;
    int experience;

    public Pair(long count, int experience) {
      this.count = count;
      this.experience = experience;
    }

    @Override
    public int compareTo(Pair o) {
      return Integer.compare(this.experience, o.experience);
    }
  }
}