import sys

stdin = sys.stdin

import numpy as np



 

ns = lambda: stdin.readline().rstrip()

ni = lambda: int(ns())

na = lambda: list(map(int, stdin.readline().split()))

s = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]



a, b = na()



print((a+b if a+b <10 else "error"))
import sys

stdin = sys.stdin



ns = lambda: stdin.readline().rstrip()

ni = lambda: int(ns())

na = lambda: list(map(int, stdin.readline().split()))



a, b = na()

print(("error" if a+b >= 10 else a+b))
import sys

stdin = sys.stdin
import numpy as np

ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
s = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)]
a, b = na()
print((a + b if a + b < 10 else "error"))

import sys

stdin = sys.stdin
ns = lambda: stdin.readline().rstrip()
ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
a, b = na()
print(("error" if a + b >= 10 else a + b))

-import numpy as np - -s = lambda h: [list(map(int, stdin.readline().split())) for i in range(h)] -print((a + b if a + b < 10 else "error")) +print(("error" if a + b >= 10 else a + b))