#include<stdio.h>
#include<string.h>
#include<ctype.h>

int isValid(char *s)
{
    for(int i=0; s[i]; i++)
    {
        if(!(isalpha(s[i])  || isspace(s[i])  || isdigit(s[i])))
        {
            return 0;
        }
    }
    return 1;
}

int main()
{
    char str[105];
    if(!fgets(str, sizeof(str), stdin))
    return 0;
    str[strcspn(str, "\n")] = '\0';
    
    if(!isValid(str))
    {
        printf("Invalid input");
        return 0;
    }
    int seen[256] = {0};
    char result[105];
    int k=0;
    
    for(int i=0; str[i]; i++)
    {
        unsigned char c= str[i];
        char lower = tolower(c);
        
        if(!seen[(int)lower])
        {
            result[k++]=c;
            seen[(int)lower]=1;
        }
    }
    result[k] = ' 0\';
    
    printf("%s", result);
    return 0;
}