I am going to make a draw by cutting a rectangular piece of paper measuring 63 centimeters (cm) wide and 42 centimeters (cm) long. Find how many centimeters (cm) the length of one side of the lottery paper should be in order to make the lottery paper square and minimize the number of people who won the lottery.
63 42 [OP_GCD]
var_a = 63
var_b = 42
var_c = math.gcd(int(var_b), int(var_a))
print(int(var_c))