public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

String inputString = sc.nextLine();

String ans = "YES";

char word[] = {'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'};

int count[] = new int[26];

char a[] = inputString.toCharArray();

int l = inputString.length();

int c=0;

for(int i=0;i<26;i++){

for(int j=0;j<l;j++){

if(word[i]==a[j])

count[i]++;

}

if(count[i]%2!=0)

c++;

if(c>1){

ans = "NO";

break;

}

}

System.out.println(ans);

}