a=input()
flg = True
for i in range(0,len(a)-1,2):
    b = a[i:i+2]
    if b[1].isspace() == False :
        flg = False
        break
    elif b[0].islower() == False:
        flg = False
        break
if a[-1].islower() and flg:
    print("Yes")
else:
    print("No")