You are given an infinite 2-d grid with the bottom left cell referenced as (1,1). All the cells contain a value of zero initially. Let's play a game?

The game consists of N steps wherein each step you are given two integers a and b. The value of each of the cells in the co-ordinate (u, v) satisfying 1 ≤ u ≤ a and 1 ≤ v ≤ b, is increased by 1. After N such steps, if X is the largest number amongst all the cells in the rectangular board, can you print the number of X's in the board?

Input: 

- The first line of input contains a single integer N. 
- N lines follow, each line contains two integers a and b separated by a single space.

Output:

Output a single integer - the number of X's.

Constraints
1 ≤ N ≤ 100
1 ≤ a ≤ 10⁶
1 ≤ b ≤ 10⁶