Why the output is 1

Question

Here is the thing, I am not sure why the output is 1

list1=[2,4,6]
list2=[1,2,3]
x=list1+list2
print(x[3])

any idea why one is correct?
is it 1 because
2 is index0
4 is index 1
6 is index 2
1 is index 3?

Answer 1

2,4,6,1,2,3
0,1,2,3
1 is in the index 3.

Answer 2

thanks