Problems
The area of a polygon
The area of a polygon
Determine the area of the polygon.
Input
The first line of one number - N
(3 ≤ N ≤ 100000
). Next N
lines in a pair of numbers - the coordinates of another vertex simple polygon in order to circumvent or counterclockwise. All coordinates are integers modulo not exceeding 10000
.
Output
One number - the area of the reduced polygon with an accuracy of 1
decimal places.
Input example #1
3 1 0 0 1 1 1
Output example #1
0.5