The thread
Misha scored a carnation in a plate, and Masha pull a thread around them and get a convex polygon, which is a smaller stud.
Since Misha once again watch soccer and he has no time, help them calculate the area of a polygon of minimal area, thereby checking the quality of work meet the following Masha.
Input
The first line of each test case contains a number of goals Mischa nails N (4 ≤ N ≤ 10^5). In the next N lines for each test case there are N pairs of numbers X_i and Y_i - the coordinates of the next nail. All coordinates does not exceed the modulo 10^9. It is guaranteed that no two are not the same nail.
Input data ending line containing 0.
Output
For each test case in a separate line output the desired area with the two characters after the decimal point.