How many ways are there to line up 5 students?
5 5 [OP_PERM]
var_a = 5
var_b = 5
var_c = 1
var_a = int(var_a)
var_b = int(var_b)
for i, elem in enumerate(range(var_b)):
    var_c = var_c * (var_a-i)
print(int(var_c))