When attaching a square picture drawn by students to a rectangular blackboard 120 centimeters (cm) wide and 96 centimeters (cm) long without any remaining parts, find how many centimeters (cm) long a side should be to maximize the size of the picture.
120 96 [OP_GCD]
var_a = 120
var_b = 96
var_c = math.gcd(int(var_b), int(var_a))
print(int(var_c))