'''****** Задание ********
  *Красота спасёт мир.
'''
num = int(input())
first = num // 100
second = num // 10 % 10
third = num % 10
if max(first, second, third) != first and min(first, second, third) != first:
    middle = first
elif max(first, second, third) != second and min(first, second, third) != second:
    middle = second
else:
    middle = third
if max(first, second, third) + min(first, second, third) == middle * 2:
    print('YES')
else:
    print('NO')