# ARC 063 A

def resolve():
  a, b = map(int, input().split())
  sum = a+b
  if sum >= 10:
    print('error')
  else:
    print(sum)


if __name__ == "__main__":
    resolve()

cdb7040eb6a6cf01ab8c1dd524ed7d866bf4ad48
<mask token>

def resolve():
    a, b = map(int, input().split())
    sum = a + b
    if sum >= 10:
        print('error')
    else:
        print(sum)


<mask token>

def resolve():
    a, b = map(int, input().split())
    sum = a + b
    if sum >= 10:
        print('error')
    else:
        print(sum)


if __name__ == '__main__':
    resolve()

# ARC 063 A

def resolve():
  a, b = map(int, input().split())
  sum = a+b
  if sum >= 10:
    print('error')
  else:
    print(sum)


if __name__ == "__main__":
    resolve()
