chees

line = input()
letters = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H']

if ((line[0] or line[3]) not in letters) or ((int(line[1]) or int(line[4])) not in range(1, 9)):
    print("ERROR")
elif abs(ord(line[0]) - ord(line[3])) == 1 and abs(int(line[1]) - int(line[4])) == 2:
    print("YES")
elif abs(ord(line[0]) - ord(line[3])) == 2 and abs(int(line[1]) - int(line[4])) == 1:
    print("YES")
else:
    print("NO")