B"Many years have passed, and n friends met at a party again. Technologies have leaped forward since the last meeting, cameras with timer appeared and now it is not obligatory for one of the friends to stand with a camera, and, thus, being absent on the photo. Simply speaking, the process of photographing can be described as follows. Each friend occupies a rectangle of pixels on the photo: the i-th of them in a standing state occupies a wi pixels wide and a hi pixels high rectangle. But also, each person can lie down for the photo, and then he will occupy a hi pixels wide and a wi pixels high rectangle. The total photo will have size W xe2 x80 x89 xc3 x97 xe2 x80 x89H, where W is the total width of all the people rectangles, and H is the maximum of the heights. The friends want to determine what minimum area the group photo can they obtain if no more than n xe2 x80 x89/ xe2 x80 x892 of them can lie on the ground (it would be strange if more than n xe2 x80 x89/ xe2 x80 x892 gentlemen lie on the ground together, isn't it?..) Help them to achieve this goal. The first line contains integer n (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n xe2 x80 x89 xe2 x89 xa4 xe2 x80 x891000) -- the number of friends. The next n lines have two integers wi, xe2 x80 x89hi (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89wi, xe2 x80 x89hi xe2 x80 x89 xe2 x89 xa4 xe2 x80 x891000) each, representing the size of the rectangle, corresponding to the i-th friend. Print a single integer equal to the minimum possible area of the photo containing all friends if no more than n xe2 x80 x89/ xe2 x80 x892 of them can lie on the ground."...