#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main(){
    char s[101];
    char result[101];
    int valid = 1;
    int i, j, k=0, duplicate;
    scanf("%[^\n]",s);
    for(i = 0; s[i] != '\0'; i++){
        if(!(isalpha(s[i]) || isdigit(s[i]) || s[i] ==' ')){
            valid = 0;
            break;
        }
    }
    if(!valid) {
        printf("Invalid input");
        return 0;
    }
    for (int i = 0; s[i] != '\0'; i++){
        if(c ==' ')
        continue;
       unsigned char lc =(unsigned char) tolower((unsigned char)c);
            if(freq[lc] == 0){
            printf("%d" , &c);
            freq[lc] = 1;
        }
    }
    return 0;
}