password = int(input())
n1 = password // 100
n2 = password // 10 % 10
n3 = password % 10
first_sum = n1 + n2
second_sum = n2 + n3
if first_sum > second_sum:
    print(str(first_sum) + str(second_sum))
elif first_sum < second_sum:
    print(str(second_sum) + str(first_sum))
else:
    print(str(first_sum) + str(second_sum))