S = input()
N = len(S)//2
alpha = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
result = "Yes"
for i in range(N):
    if S[2*i] in alpha and S[2*i+1] == " ":
        pass
    else:
        result = "No"
print(result)