#include<stdio.h>
#include<conio.h>
int main() 
{
    char s[101], result[101];
    int used[256] = {0};
    int i, j = 0;

    gets(s);

 
    for (i = 0; s[i] != '\0'; i++) {
        char ch = s[i];
        if (!(ch >= 'A' && ch <= 'Z') &&
            !(ch >= 'a' && ch <= 'z') &&
            !(ch >= '0' && ch <= '9') &&
            ch != ' ') {
            printf("Invalid input\n");
            return 0;
        }
    }

    // Remove repeated characters
    for (i = 0; s[i] != '\0'; i++) {
        if (used[(unsigned char)s[i]] == 0) {
            result[j++] = s[i];
            used[(unsigned char)s[i]] = 1;
        }
    }

    result[j] = '\0';
    printf("%s\n", result);

    return 0;
}