#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main()
{
    chars[1000];
    int seen[256]={0};
    if(!fgets(s,sizeof(s),stdin))
    {
        printf("Invalid Input");
        return 0;
     }
     int len=strlen(s);
     if(s[len-1]=='\n')
     s[len-1]='\0';
     
     char result[1000];
     int idx=0;
     for(int i=0;s[i]!='\0';i++)
     {
         char c=s[i];
         if(isalnum(c)||c=='')
         {
             if(!seen[(unsigned
             char)c])
             {
                 result[idx++]=c;
                 seen[(unsigned char)c]=1;
            
             }
         }
     }
     result [idx]='\0';
     printf("%s", result);
     return 0;
}