PE Class

During PE class, the coach Andrey Sergeevich lines up the students in a single row. The boys stand first, followed by the girls. The boys are arranged in descending order of height, and the girls are too. So the shortest boy is directly followed by the tallest girl.

Andrey Sergeevich wants to know the largest height difference between two students standing next to each other. Write a program that answers this question.

The first line contains an integer $n$, the number of students in the class ($2 \le n \le 50$). Each of the next $n$ lines contains two integers $a_i$ and $h_i$, the sex and height in centimeters of the $i$-th student ($100 \le h_i \le 200$). $a_i = 0$ means the $i$-th student is a boy, and $a_i = 1$ means the $i$-th student is a girl.

Print one integer, the largest height difference between two students standing next to each other after they line up for PE class.