Rectangles

For the given N rectangles, your task is to find the smallest area that can be covered by these rectangles, allowing them to overlap. Each rectangle is defined by the lengths of its two sides.

Input

The first line contains the integer N, representing the number of rectangles. This is followed by N lines, each containing two integers that specify the lengths of the sides of a rectangle (1 ≤ N ≤ 2·10^5, and the lengths of the sides do not exceed 10^9).

Output

Output a single line containing the smallest possible area that can be covered by the rectangles.

Examples