f = open('INPUT.TXT')
line = f.readline().strip().split()
f.close()

start = line[0]
end = line[1]

start_col = ord(start[0]) - ord('a')
start_row = int(start[1]) - 1

end_col = ord(end[0]) - ord('a')
end_row = int(end[1]) - 1

can_reach = False

if end_row > start_row:
    diff_row = end_row - start_row
    diff_col = abs(end_col - start_col)
    
    if diff_row == diff_col:
        can_reach = True

f = open('OUTPUT.TXT', 'w')
if can_reach:
    f.write('YES')
else:
    f.write('NO')
f.close()