#include<stdio.h>
 #include<string.h>
 #include<ctype.h>
 int main()
 {
     char s[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;
             
     }