Triangle on the Axis

You are given a set of points on a plane with integer coordinates. Find a triangle with the largest area whose vertices belong to this set of points, with one of its sides lying on the $Ox$ axis.

The first line contains an integer $n$: the number of points ($1 \le n \le 1000$). Each of the following $n$ lines contains two integers $x$ and $y$: the coordinates of the points. All coordinates do not exceed $1000$ by absolute value.

Output a single real number: the maximum area of the triangle that satisfies the problem's conditions. If there is no such triangle or it is degenerate, output $0$.

Your answer will be considered correct if it differs from the exact value by no more than $10^{-9}$.

Pictures for the examples: