Backpacking

O = A + B

Test 1

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 1, in <module>
    O = A + B
NameError: name 'A' is not defined

Test 2

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 1, in <module>
    O = A + B
NameError: name 'A' is not defined

Test 3

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 1, in <module>
    O = A + B
NameError: name 'A' is not defined

Test 4

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 1, in <module>
    O = A + B
NameError: name 'A' is not defined