#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main()
{
char s[1000],result[1000];
int seen[256]=[0];
int i,j=0;
fgets(s,sizeof(s),stdin);
for(i=0;s[i]!="\0";i++)
{
char c=s[i];
if(isalnum(c)||c=="")
{
if(!seen[(unsigned char)c]){
result[j++]=c;
seen[(unsigned char)c]=1;
}
}
}
result[j]="\0";
printf("%s",result);
return o;
}