A = set([chr(i) for i in range(97,123)])
S = input()
flag = "Yes"
for i in range(len(S)):
    if i%2==0:
        if S[i] in A:
            continue
        flag = "No"
        break
    else:
        if S[i]==" ":
            continue
        flag = "No"
        break
print(flag)