#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main() {
    char s[1000];
    int seen[256] = {0};
    fgets(s, sizeof(s), stdin);
    s[strcspn]
    int j=0;
    for (int 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\n", result);

    return 0;
}