Balanced Lineup

Fans stand in one line at distinct x-coordinates. You may choose a group consisting of consecutive people in this line. A group is balanced if it contains the same number of men and women.

The length of a group is the difference between the smallest and largest x-coordinate in that group. Find the maximum length among all balanced groups.

The first line contains the number of fans N (1 ≤ N ≤ 1,000,000).

Each of the next N lines contains a gender value and an x-coordinate, separated by a space. Gender is given as 0 for a man and 1 for a woman. Each x-coordinate is between 0 and 1,000,000,000 inclusive, and no two fans stand at the same x-coordinate. At least one fan of each gender exists.

Print the length of the longest group satisfying the condition.