#include <iostream> #include <string> using namespace std;  void sort(string s) {   char tmp[100];   int len=s.size();   int count=0,i,j;   for (i=0;i<len;i++)   {    for (j=i+1;j<len;j++)    {     if (s[i]==s[j])     {      s[j]='0';     }    }    }    for (i=0;i<len;i++)   {    if (s[i]>='a' && s[i]<='z')    {     tmp[count++]=s[i];    }   }    //冒泡排序   for (i=0;i<count;i++)   {    for (j=0;j<i;j++)    {     char temp;     if (strcmp(&tmp[j],&tmp[i])>0)     {      temp=tmp[j];      tmp[j]=tmp[i];      tmp[i]=temp;     }    }   }     for (i=0;i<count;i++)   cout<<tmp[i];    cout<<endl; }  void main() {  string s;  cin>>s;  sort(s); }