//問(line:17)
//您的答案為: yes !
//正確答案為: no...
#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
int main()
{
char str[1000] = {};
while(cin>>str)
{
int len = strlen(str);
//cout << len << endl;
for (int i = 0; i < len; i++) //小寫轉大寫
{
if('a'<=str[i]&&str[i]<='z')
{
str[i] = (char)((int)(str[i] - 32));
//cout << str[i] << " ";
}
}
//cout << endl;
for (int i = 0; i < len; i++) //只留英文字母
{
if(str[i]<'A'||'Z'<str[i])
{
for (int j = i; j < len; j++)
{
str[i] = str[i + 1];
}
len--;
i--;
}
}
int ascii[len];
for (int i = 0; i < len; i++) //將字元轉成ascii以便排序
{
ascii[i] = (int)str[i];
}
sort(ascii, ascii + len);
for (int i = 0; i < len; i++)
{
str[i] = (char)ascii[i];
//cout << str[i] << " ";
}
//cout << endl;
int count = 1;
int strnum[len]; //出現次數
int j = 0;
for (int i = 1; i <= len; i++)
{
if(str[i-1]==str[i])
{
count++;
}
else
{
strnum[j] = count;
j++;
count = 1;
}
}
int odd = 0;
for (int i = 0; i < j; i++)
{
if(strnum[i]%2!=0)
{
odd++;
}
if(odd>1)
{
break;
}
//cout << strnum[i] << " ";
}
//cout << endl;
if(odd>1)
{
cout << "no..." << endl;
}
else
{
cout << "yes !" << endl;
}
}
return 0;
}