There are four types of animals in the fence: chicken, duck, rabbit, and dog. Find a way to get 15 animals out of the fence.
4 1 [OP_SUB] 15 [OP_ADD] 15 [OP_COMB]
var_a = 4
var_b = 1
var_c = var_a - var_b
var_d = 15
var_e = var_c + var_d
var_f = 15
var_g = 1
var_e = int(var_e)
var_f = int(var_f)
for i, elem in enumerate(range(var_f)):
    var_g = var_g * (var_e-i)
for i, elem in enumerate(range(var_f)):
    var_g = var_g / (i+1)
print(int(var_g))