s = input()
for i,v in enumerate(s):
    
    if (i+1)%2==1:
        if v.isalpha() and v.islower():
            continue
        else:
            print("No")
            exit()
    else:
        if len(v.strip())==0:
            continue
        else:
            print("No")
            exit()
print("Yes")