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1058. Chocolate

Time limit: 1.0 second
Memory limit: 64 MB
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.

Input

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

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

Sample

inputoutput
4
0 0
4 0
4 3
0 3
3
Problem Source: Rybinsk State Avia Academy