Among Rat, Cow, Tiger, Rabbit, Dragon, and Snake, find the number of cases in which the rat is placed at the very front, the snake at the very back, and the rest are placed in one line.
[OP_LIST_SOL] Rat Cow Tiger Rabbit Dragon Snake [OP_LIST_EOL] [OP_LIST_SOL] Rat [OP_LIST_EOL] [OP_SET_DIFFERENCE] [OP_LIST_SOL] Snake [OP_LIST_EOL] [OP_SET_DIFFERENCE] [OP_LIST_LEN] [OP_LIST_LEN] [OP_PERM]
var_a = 'Rat'
var_b = 'Cow'
var_c = 'Tiger'
var_d = 'Rabbit'
var_e = 'Dragon'
var_f = 'Snake'
list_a= []
if "/" in str(var_f):
    var_f = eval(str(var_f))
list_a.append(var_f)
if "/" in str(var_e):
    var_e = eval(str(var_e))
list_a.append(var_e)
if "/" in str(var_d):
    var_d = eval(str(var_d))
list_a.append(var_d)
if "/" in str(var_c):
    var_c = eval(str(var_c))
list_a.append(var_c)
if "/" in str(var_b):
    var_b = eval(str(var_b))
list_a.append(var_b)
if "/" in str(var_a):
    var_a = eval(str(var_a))
list_a.append(var_a)
list_a.reverse()
var_g = 'Rat'
list_b= []
if "/" in str(var_g):
    var_g = eval(str(var_g))
list_b.append(var_g)
list_b.reverse()
list_c = list(set(list_a) - set(list_b))
var_h = 'Snake'
list_d= []
if "/" in str(var_h):
    var_h = eval(str(var_h))
list_d.append(var_h)
list_d.reverse()
list_e = list(set(list_c) - set(list_d))
var_i = len(list_e)
var_j = len(list_e)
var_k = 1
var_i = int(var_i)
var_j = int(var_j)
for i, elem in enumerate(range(var_j)):
    var_k = var_k * (var_i-i)
print(int(var_k))