PROGRAMMING:Calculation of shadow area based on inclusion exclusion principle
The inclusion exclusion principle is an important combinatorial method, which allows you to solve sets of any size, or calculate the probability of composite events. It can be described as calculating the size of the union of several sets. We need to first calculate the size of all single sets, and then subtract the part where all two sets intersect, add back the part where all three sets intersect, and then subtract the part where all four sets intersect. According to this deduction, we can calculate until the part where all sets intersect.
As shown in the figure above, if sets a and B are known, then | a ∪ B | = | a | + | B | - | a ∩ B |;
If the set a, B, C is known, then | a ∪ B ∪ C | = | a | + | B | + | C | - | a ∩ B | - ゝ B ∩ C | - ゝ C ∩ a | + | a ∩ B ∩ C |. The rectangle ABCD is now known. Take AB as the radius to make the extension line of sector intersection ad at F, and CB as the radius to make the sector intersection CD at F. as shown in the figure below, the length and width of the rectangle are known as X and Y respectively, and the area of the shadow part is calculated.
Note: 1. The area formula of sector: S = n π R ^ 2 / 360 = LR / 2 (where n is the degree of the center angle of the sector, R is the sector radius, l is the arc length, π = 3.1415926)
2. Area formula of rectangle: S = AB (where a and B are length and width respectively)
###Input format:
Input in a line to give two positive real numbers x and y no more than 100, and ensure that x > = Y > = 1.
###Output format:
Output the area of the shadow in one row, leaving the result to two decimal places.
###Input example:
Here is a set of inputs. For example:
```in
6 5
```
###Output example:
The corresponding output is given here. For example:
```out
seventeen point nine one
```
answer：If there is no answer, please comment
As shown in the figure above, if sets a and B are known, then | a ∪ B | = | a | + | B | - | a ∩ B |;
If the set a, B, C is known, then | a ∪ B ∪ C | = | a | + | B | + | C | - | a ∩ B | - ゝ B ∩ C | - ゝ C ∩ a | + | a ∩ B ∩ C |. The rectangle ABCD is now known. Take AB as the radius to make the extension line of sector intersection ad at F, and CB as the radius to make the sector intersection CD at F. as shown in the figure below, the length and width of the rectangle are known as X and Y respectively, and the area of the shadow part is calculated.
Note: 1. The area formula of sector: S = n π R ^ 2 / 360 = LR / 2 (where n is the degree of the center angle of the sector, R is the sector radius, l is the arc length, π = 3.1415926)
2. Area formula of rectangle: S = AB (where a and B are length and width respectively)
###Input format:
Input in a line to give two positive real numbers x and y no more than 100, and ensure that x > = Y > = 1.
###Output format:
Output the area of the shadow in one row, leaving the result to two decimal places.
###Input example:
Here is a set of inputs. For example:
```in
6 5
```
###Output example:
The corresponding output is given here. For example:
```out
seventeen point nine one
```
answer：If there is no answer, please comment
