Introduction to Python

# Combining zip and enumerate

Sometimes, we might want to know the indices for zipped lists. In that case, we can use `enumerate()` on top of `zip()`. Yet, it’s essential to understand what each of those functions does. Zip returns a tuple for each element pair of list elements. Enumerate returns a tuple for each element of a list. Therefore the resulting structure will be tuple of tuples:
``````a = [1, 2, 3, 4]
b = [5, 6, 7, 8]
zip(a, b)             # [(1, 5), (2, 6), (3, 7), (4, 8)]
enumerate(a)          # [(0, 1), (1, 2), (2, 3), (3, 4)]
enumerate(b)          # [(0, 5), (1, 6), (2, 7), (3, 8)]
enumerate(zip(a, b))  # [(0, (1, 5)), (1, (2, 6)), (2, (3, 7)), (3, (4, 8))]

# Therefore, we need to loop over the elements with tuples:
for i, (item1, item2) in enumerate(zip(a, b)):
print(f'index: {i} => a[i]={item1} and b[i]={item2}')

# index: 0 => a[i]=1 and b[i]=5
# index: 1 => a[i]=2 and b[i]=6
# index: 2 => a[i]=3 and b[i]=7
# index: 3 => a[i]=4 and b[i]=8``````
Notice how `item1` and `item2` are wrapped to form a tuple, in the `for` loop.

#### Challenge

Given 3 lists each on a separate line, you are asked to create a new list from those which will represent the sum of the elements of the 3 lists, while skipping the values at odd locations (indexing starts at 0).
The input contains 3 lines - each one contains numbers separated by a space.
The program should print a single line - the resulting list.
 Input Output 1 2 3 4 5 6 7 8 9 10 11 12 15 21
Can you solve this in a single line 😎?

#### Constraints

Time limit: 1 seconds

Memory limit: 512 MB

Output limit: 1 MB