# How to determine which variables to add and which to not add together?

Just started to learn Python and got stuck immediately. I have to add together variables that are greater than 0. So e.g. if I had these variables:

``````num1 = 5
num2 = 5
num3 = 0
num4 = -5
num5 = 5
``````

I’d like to add together 1, 2 and 5 (total 15) and exclude 3 and 4.
I guess I could use

``````if num1 <= 0:
print(num2 + num3 + num4 + num5)
else:
print(num1 + num2 + num3 + num4 + num5)
``````

and go through every variable like this but it sounds really unconvenient and awkward. How should I do it with one command? Thanks.

### >Solution :

It’s better to store the values in a list, rather than in five different variables. And then it will be easy to use for loop or list comprehension, for example, to do what you want.

Using for-loop:

``````lst = [5, 5, 0, -5, 5]

output = 0
for x in lst:
if x > 0:
output += x
print(output) # 15
``````

Using list comprehension (more precisely, generator expression):

``````lst = [5, 5, 0, -5, 5]

output = sum(x for x in lst if x > 0)
print(output) # 15
``````