Using all single-digit whole numbers greater than 6 once, find the sum of the largest three-digit number and the third largest three-digit number.
6 1 [OP_ADD] 9 1 [OP_LIST_ARANGE] 3 [OP_LIST_GET_PERM] 1 [OP_LIST_MAX] 3 [OP_LIST_MAX] [OP_ADD]
var_a = 6
var_b = 1
var_c = var_a + var_b
var_d = 9
var_e = 1
list_a = [i for i in range(var_c, var_d + 1, var_e)]
var_f = 3
list_b = [str(i) for i in list_a]
list_b = list(itertools.permutations(list_b, var_f))
list_b = [''.join(num_list) for num_list in list_b]
list_b = [str_num for str_num in list_b if str_num[0] != '0']
list_b = [float(i) for i in list_b]
var_g = 1
list_c=list_b.copy()
list_c.sort()
var_h = list_c[-var_g]
var_i = 3
list_d=list_b.copy()
list_d.sort()
var_j = list_d[-var_i]
var_k = var_h + var_j
print(int(var_k))