Shortest python A + B program with input and output
Given the right hint toward the solution in the comment to the same question asked on stackoverflow ( see here ), I have got it right down to 34 and without any limitations on the input number or other tricks necessary:
print(eval(input().replace(*' +')))
Here a short summary of currently known different solutions:

print(eval(input().replace(' ','+')))  # 36
print(sum(map(int,input().split())))   # 36
print(eval(input().replace(*' +')))    # 34
print(sum(map(int,input()[::2])))      # 33 (limited to numbers between 0 and 9)

Maybe it could be considered cheating, but maybe not. At least there is no rule for this defined yet so let's include it into the collection of possible solutions:

import f;f.f()                         # 13

Required for this solution to work is a script f.py available in a search directory for modules of Python with following content:
def f():
    print(sum(map(int,input().split())))