import math

num = int(input())
print
while True:
    if num >= 1 and num <= 15:
        if num == 15:
            result = str(round(math.pi, num))
            break
        else:
            result = str(round(math.pi, num+1))
            result = result[:-1]
            break
    else: 
        num =int(input())
print(result)

정리

1 3.1 2 3.14 3 3.141 4 3.1415 5 3.14159 6 3.141592 7 3.1415926 8 3.14159265 9 3.141592653 10 3.1415926535 11 3.14159265358 12 3.141592653589 13 3.1415926535897 14 3.14159265358979 15 3.141592653589793