#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main()
{
  char str[101],result[101];
  int seen[256]={0};
  int k=0;
 if(!fgets(str,sizeof(str),stdin))
 {
   printf("Invalid Input");
   return 0;
 }
 str[strcspn(str,"\n")]='\0';
 int n=strlen(str);
 if(n<1||n>100)
 {
     printf("Invalid Input");
     return 0;
 }
 for(int i=0;i<n;i++)
 {
     charc=str[i];
     if(!(isalpha(c)||isdigit(c)||c==''))
     {
         printf("Invalid Input");
         return 0;
     }
     if(!seen[(unsigned char)c])
     {
         result[k++]=c;
         seen[(unsigned char)c]=1;
     }
 }
   result[k]='\0';
   printf("%s",result);
   return 0;
}