Olympiad programming in python obscure runtime error?

Question

Programming

Here is a link to the task I'm trying to solve
Link to the task
And here is the code that the NOC finds for me, but when checking, the system issues a runtime error, what could be the problem?

import math
r = open("input.txt")
w = open("output.txt","w")
A,B = map(int,r.readline().split())
w.write(str((A*B / math.gcd(A,B))))
r.close()
w.close()

Answer 1

The problem is something, since you do not realize that the full error output is needed.

Answer 2

the problem is that there is no gcd function in the math module