If the hundreds digit of a three-digit natural number is 5, the tens digit is 1, and the units digit is 3, what is this number?
[OP_LIST_SOL] 5 1 3 [OP_LIST_EOL] [OP_LIST2NUM]
var_a = 5
var_b = 1
var_c = 3
list_a= []
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_d=""
for i in list_a:
    i = str(i)
    var_d = var_d + i
print(int(var_d))