题目 2201: # Twin Buildings(H)

时间限制: 1s
内存限制: 256MB 提交: 13 解决: 5

As you might already
know, space has always been a problem in ICPC Jakarta. To cope with this, ICPC
Jakarta is planning to build **two** new buildings. These buildings should
have a shape of a rectangle of the same size. Now, their problem is to find
land to build the buildings.

There are *N*lands available for sale. The *ith* land has a rectangular shape of size *Li*×*Wi* For a good
feng shui, the building's side should be parallel to the land's sides.

One way is to build the two
buildings on two different lands, one on each land (not necessarily with the
same orientation). A building of size *A*×*B *can be build on the *ith* land if and only if at least one of the following is satisfied:

· *A*≤*Li* and *B*≤*Wi* or

· *A*≤*Wi* and *B*≤*Li* .

Alternatively, it is also possible
to build two buildings of *A*×*B*on the *ith* land with the same orientation. Formally, it is possible to build two
buildings of *A*×*B* on the *ith* land if and only if at least one of the following is satisfied:

· *A*×2≤*Li* and *B*≤*Wi*, or

· *A*×2≤*Wi *and *B*≤*Li*, or

· *A*≤*Li* and *B*×2≤*Wi*, or

· *A*≤*Wi *and *B*×2≤*Li*.

Input begins with a line
containing an integer: *N* (1≤*N*≤100000) representing the number
of available lands. The next *N* lines each contains two integers: *Li* *Wi* (1≤*Li*,*Wi*≤10^{9}) representing the size of the land.

Output in a line a number representing the largest building that ICPC Jakarta can build with exactly one decimal point (see sample input/output for clarity).

2 5 5 3 4

12.5