# This program demonstrates a function with a side effect.
# Each time f is called, the variable x's value changes.

x = 5

def f(n):
    global x
    x = x * 2
    return x + n

def main():
    global x
    x = 5
    result = f(x) + f(x)
    print("result is", result)
    print("x is", x)

main()