// editor1
#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main()
{
char str[101];
int freq[256]={0};
fgets(str,sizeof(str),stin);
str[strscpr(str,"\n")]='\0';
for(int i=0;str[i];i++)
{
    if(!isalnum(str[i])&&str[i]!='')
    {
        printf("Invalid input\n");
        return 0;
    }
}
for(int i=0;str[i];i++)
{
    if(freq(unsigned char)str[i]==0)
    {
        printf("%c",str[i]);
        freq(unsigned char)str[i]==1;
    }
}
printf("\n");
return 0;
}