You have a rectangular piece of paper measuring 63 centimeters (cm) wide and 42 centimeters (cm) long. You want to cut several pieces of this paper into the largest square shapes without any remainder. How many centimeters (cm) should each side of the square be?
63 42 [OP_GCD]
var_a = 63
var_b = 42
var_c = math.gcd(int(var_b), int(var_a))
print(int(var_c))