import sys

def add_number(x):
  # double every other
  d = []
  for o, n in enumerate(x):
    if (o % 2):
      d.append(int(n)*2)
    else:
      d.append(int(n))
  # sum the numbers
  total = 0
  for n in d:
    for c in str(n):
      total += int(c)
  return total

def add_check(x):
  print "{} check: {}".format(x, add_number(x) * 9 % 10)

def verify_check(x):
  total = add_number(x[:-1])
  if (total * 9 % 10) == int(x[-1]):
    return True
  return False

if __name__ == '__main__':
  if len(sys.argv) != 2:
    add_check(sys.argv[2])
  else:
    print verify_check(sys.argv[1])