4589: P1183 多边形的面积
Memory Limit:128 MB
Time Limit:1.000 S
Judge Style:Text Compare
Creator:
Submit:0
Solved:0
Description

Input

Output

Sample Input Copy
10
0 0
4 0
4 1
3 1
3 3
2 3
2 2
1 2
1 3
0 3
Sample Output Copy
9
HINT
