#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main()
{
    char s[101];
    int seen[256]={0};
    char result[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 intput");
            return 0;
        }
    }
    for(i=0;s[i]!= '\0';i++){
        char ch = s[i];
        char lower = tolower(ch);
        if(!seen[(unsingned char)lower]){
            result[j++] = ch;
            seen[(unsigned char)lower] = 1;
        }
    }
    result[j] = '\0';
    printf("%s", result);
    return 0;
}