I can help. You are running into an assignment vs. comparison problem. If you say f=1 you are assigning the value 1 to the variable f. If you say something like f==1, you are checking is the variable f equal to 1 and returning a true/false depending on if it is or not. So on line 71 the first = should be ==, but your second = should remain just =. The >= is fine as is too.