F. Rect
time limit per test
1 second
memory limit per test
4 megabytes
input
standard input
output
standard output

Given points on a plane, output the area of a rectangle with its sides parallel with the coordinate axes that contains inside or on the sides at least points of the points given.

Input

The input file drept.in contains on the first lines 2 numbers and each of the following lines contains 2 numbers and describing the th point.

Output

The output file drept.out contains the required area.

Example
Input
13 7
5 5
7 8
6 8
5 8
4 6
6 3
4 2
8 0
9 2
3 4
7 8
5 4
5 3
Output
10