#include <bits/stdc++.h>
using namespace std;
void Encrypt(char* keych, char* key);
int main() {
  char key[100], data[100], encrypt[100];
  char keych[100];
  fgets(key, 100, stdin);
  Encrypt(keych, key);
  cout << keych;
  return 0;
}
void Encrypt(char* keych, char* key) {
  keych[0] = key[0];
  int i, j = 0, k = 0, flag;
  for (i = 0; key[i] != '\0'; i++) {
    flag = 1;
    for (k = 0; k < j + 1; k++) {
      if (key[i] == keych[k]) flag = 0;
    }
    if (flag) {
      j = j + 1;
      keych[j] = key[i];
    }
  }
  keych[j + 1] = '\0';
}
