#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main(){
    char str[101];
    int seen[256]={0};
    int i;
    fgets(str,sizeof(str),stdin);
    str[strcspn(str,"\n")]='\0';
    for(i=0;str[i]!='\0';i++){
        if(!(isalnum((str[i])||str[i]==' ')){
            printf("Invalid Input");
            return 0;
        }
    }
    for(i=0;str[i]!='\0';i++){
        if(str[i]==' ') continue;
        char lower = tolower(str[i]);
        if(!seen[(unsigned char)lower]){
            printf("%c",str[i]);
            seen[(unsigned char)lower]=1;
        }
    }
    printf("\n");
    return 0;
}