#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main()
{
 char s[101];
 int see[256];
 char re[101];
 int i,j=0;
 fgets(s,sizeof(s),stdin);
 s[strcmp(s,"\n")]='\0';
 for(i=0;s[i]!='0';i++){
 if(!(isalnum(s[i] || s[i] ==' '))) {
 printf("Invalid input");
 return 0;
 }
 
 for(i=0 ; s[i]!='\0';i++){
 char ch =s[i];
 char lower = tolower(ch);
 if(!see[(unsigned char)lower]){
 re[j++]=ch;
 see[(unsigned char)lower]=1;
 }
 }
 re[j]='\0';
 printf("%s",re);
 return 0;
 }