// editor1
#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main()
{
char str[100];
int i,j,len;
int seen[256] = {0};
int valid=1;
fgets(str,sizeof(str),stdin);
str[strcspn(str,"\n")]='\0';
len=strlen(str);
for(i=0;i<len;i++) {
if (!(isalnum(str[i]) || str[i]=='')) {
valid=0;
break;
}
}
if (!valid) {
printf("Invalid input\n");
return 0;
}
for (i=0;i<len;i++) {
if (!seen[(unsigned char)str[i]]) {
printf("%c",str[i]);
seen[(unsigned char)str[i]]=1;
}
}
printf("\n");
return 0;
}