#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main()
{
    char s[101];
    int see[256]={0};
    char re[101];
    int i,j=0;
    fgets(s,sizeof(s),stdin);
    s[strcspn(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]){
        result[j++]=ch;
        see[(unsigned char)lower]=1;
    }
}
re[j]='\0';
printf("%s",re);
return 0;
}