#Write an assignment statement for the following mathematical equation:
#y = (1/3)x + (x/4) + 2x

#Keep x as an integer. Use an expression that matches the equation's right side as closely as possible. If the input is -1, the output is -2.58333.

#Hints:
#Don't rearrange the equation or try to simplify it.
#If both operands of division (or other operators) are integers, 
#integer division is performed, which rounds down; 

#so for example 1/2 is 0. So make at least one operand a floating-point type, as in 1.0/2, or 1.0/2.0, to cause floating-point division.


x = int(input())

y = ((1.0 / 3.0) * x) + (x / 4. 0) + (2.0 * x); 

print(round(y, 5))