Among the people of A, B, C, and D, two people are selected, one to be the president and the other to be the vice president. Find the number of possible cases.
[OP_LIST_SOL] A B C D [OP_LIST_EOL] [OP_LIST_LEN] 2 [OP_PERM]
var_a = 'A'
var_b = 'B'
var_c = 'C'
var_d = 'D'
list_a= []
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_e = len(list_a)
var_f = 2
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)
print(int(var_g))