#include<stdio.h>
#include<ctype.h>
#include<string.h>
int main(){
    char s[105],seen={0};
    fgets(s,sizeof(s),stdin);
    for(int i=0;s[i];i++){
        if(!(isalnum((unsigned char)s[i])||s[i]==''||s[i]=='\n')){
            printf("Invalide input\n");
            return 0;
    }
}
for(int i=0;s[i];i++){
    unsigned char c=s[i];
    if (!seen[c] && c!='\n'){
        putchar(c);
        seen[c]=1;
    }
}
printf("\n");
return 0;
}