Fishburg confectionery factory produces convex polygon-shaped chocolates. Little Boy and Karlsson bought one and wanted to break it into two fragments. The areas of the fragments must be equal. Create a code to find out the length of breakage-line of a minimal length using the given chocolate form.

The first line of input contains an integer N — the number of polygon vertices (4 ≤  N ≤ 50). The other N lines contain coordinates of the vertices in the counter-clockwise order. Coordinates are real numbers from −100 to 100 and given with at most 3 digits after decimal point.

Output should contain the minimal length of breakage-line with accuracy to 0.0001.