Because Tianyi thought that bury the evidence one by one is too slow, she came up another idea.
The area is N * N, but because Tianyi has already buried some area, it's not a square now.
Think of that the left hole is N units width. For each unit of the N width, it stretch to two sides vertically.

For example, the hole stretches from -1 to 2 at the first unit and the hole stretches from -2 to 3 at the second unit, and it's like the picture below:

But Tianyi is too lazy to bury all of it, so she find a rectangle to cover it. To cover evidence as more as Tianyi can, she must make the rectangle largest.
Can you help Tianyi to find a largest rectangle in the hole area? (The rectangle must be put vertically or horizontally and you can't rotate it).

This problem has several cases.
The first line of each case is an integer N (1 <= N <= 100,000), indicates the width of the hole area.
Next follow N lines, each line has two integers Di and Ui (-10000 <= Di <= 0 <= Ui <= 10000), indicate the vertical stretch of each unit.

For each case, you should output the maximum area of the rectangle in the hole area.