#include<stdio.h>
#include<ctype.h>
#include<string.h>
int main()
{
    char str[101], result[101];
    int i,j = 0;
    fgets(str, sizeof(str), stdin);
    str[strcspn(str, "\n")] = '\0';
    int len = strlen(str);
    for(i = 0; i < len; i++)
    {
        if(!(isalpha(str[i]) || str[i] == ' '))
        {
            printf("Invalid input");
            return 0;
        }
    }
    for (i = 0; i < len; i++)
    {
        int found = 0;
        if (str[i] == ' ')
            contine;
            for (int k = 0; k < j; k++)
          {
              if (result[k] == str[i])
              {
                  found =1;
                  break;
              }
          }
          if (!found)
          {
              result[j++] = str[i];
          }
    }
     result[j] = '\n;
    printf("%s", result);
    return 0;
}