Problem Description

Given the coordinates of three points $A$ , $B$ , $C$ . Find the area of the right triangle formed by these points.

Input Format

The input contains six values: $X_A$ , $Y_A$ , $X_B$ , $Y_B$ , $X_C$ , $Y_C$ . All values do not exceed $10^9$ in absolute value. It is guaranteed that the segments $AB$ and $AC$ are the legs of the triangle.

Output Format

Output the area value rounded to six decimal places.

Examples

Example 1

Input

0 0
3 0
0 4

Output

Example 2