s=input() s1,s2='','' if(len(s)%2==0): s1=s[:len(s)//2] s2=s[len(s)//2:] else: s1=s[:len(s)//2] s2=s[len(s)//2+1:] l1=list(s1) l2=list(s2) l1.sort() l2.sort() s1=str(l1) s2=str(l2) if(s1==s2): print('YES') else: print('NO')