S=input()
if len(S)%2!=0:
    print("No")
elif len(S)!=2 and S[0:int((len(S)/2)-1)]==S[int((len(S)/2)):len(S)-1]:
    print("Yes")
elif len(S)==2:
    if S[0]==S[1]:
        print("Yes")
    else:
        print("No")
    
else:
    print("No")