The square-shaped fabric was buttoned regularly without gaps. If the number of buttons on the perimeter is 84, how many buttons are on one outermost side?
84 4 [OP_SUB] 4 [OP_DIV] 2 [OP_ADD]
var_a = 84
var_b = 4
var_c = var_a - var_b
var_d = 4
var_e = var_c / var_d
var_f = 2
var_g = var_e + var_f
print(int(var_g))