a,b = list(map(int,input().split()))

if (a + b) < 10:

	print(a+b)

else:

	print("error")
a,b = list(map(int,input().split()))

sum = a+b

if sum >= 10:

   print("error")

else:

  print(sum)
a, b = list(map(int, input().split()))
if (a + b) < 10:
    print(a + b)
else:
    print("error")

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

-if (a + b) < 10: -    print(a + b) +sum = a + b +if sum >= 10: +    print("error") -    print("error") +    print(sum)