a,b = (int(x) for x in input().split())

if a+b < 10:

  print((a+b))

else:

  print ('error')

A,B = list(map (int, input (). split ()))

if A+B>=10:

  print ('error')

else:

  print((A+B))
a, b = (int(x) for x in input().split())
if a + b < 10:
    print((a + b))
else:
    print("error")

A, B = list(map(int, input().split()))
if A + B >= 10:
    print("error")
else:
    print((A + B))

-a, b = (int(x) for x in input().split()) -if a + b < 10: -    print((a + b)) +A, B = list(map(int, input().split())) +if A + B >= 10: +    print("error") -    print("error") +    print((A + B))