import string
S = input()
ans = 'Yes'
for i in range(len(S)):
    if i % 2 == 0:
        if string.ascii_lowercase.count(S[i]) == 0:
            ans = 'No'
            break
    else:
        if ' '.count(S[i]) == 0:
            ans = 'No'
            break
print(ans)