#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main() {
char str[105], result[105];
int i , j, k = 0;
int seen[256] = {0};
fgets(sta, sizeof(str), stdin);
str[strcspn(str, "\n")] = '\0' ;
for (i = 0;str[i]; i++) {
    if (!(isalnum(stre[i])||str[i]==' ')){
        printf("invalid input");
        return 0;
    }
    }
for(i=0;str[i];i++){
    if(!seen[(unsigned char)str[i]]){
        result[k++]=str[i];
        seen[(unsigned char)str[i] ]=1;
    }
}
result[k]='\0';
printf("%s",result);
return 0;
}