Create Calculate area and perimeter of N-agon(polygon)(hw5_4)

Problem Description
Calculate area and perimeter of N-agon(polygon)。

(hint: use structure type to save the coordinate of point)

Input
N (3<=N<=10)

Coordinate of point (-1000000.000<=x,y<=1000000.000)

Output
the area and perimeter of N-agon(polygon) (third decimal)

Sample Input
3
1 1 
2 3
3 4
Sample Output
0.500 7.256