Description: Problem description
A given circle radius r, and the area of a circle.
Input format
Input contains an integer r, said the radius of the circle.
The output format
Output a line contains a real number, rounded after the decimal point 7, said the area of a circle.
Note: in the ontology, the input is an integer, but the output is a real number.
Answer to the question of the real output please see real output requirements, such as the subject of seven after decimal point, is the output of your application must be strictly 7 decimal places, the output of decimal digits too little or too much is not enough, will be considered.
The problem of real output if there are no special instructions, rounding is each round.
The sample input
4
Sample output
50.2654825
The data scale and conventions
1 < = r < = 10000.
prompt
Subject to the precision demand is higher, please pay attention to the value of PI should take more accurate values. You can use a constant to represent the PI
To Search:
File list (Check if you may need any files):
2.圆的面积\圆的面积.cpp
..........\圆的面积.exe
..........\圆的面积.o
2.圆的面积
Download