class M{
  static String c(char[] q){
    java.util.Arrays.sort(q);
    char a[] = new String(q).replaceAll("(.)\\1", "$1").toCharArray(),
         c = 97,
         i = 2;
    String r = "",
           z = "",
           s;
    for(; c < 'z'; z += c++);
    while(i < a.length){
      if(z.contains(s = "" + a[i - 2] + a[i - 1] + a[i++])){
        r += s+" ";
      }
    }
    return r;
  }

  public static void main(String[] a){
    System.out.println(c("education".toCharArray()));
    System.out.println(c("foghorn".toCharArray()));
    System.out.println(c("cabaret".toCharArray()));
    System.out.println(c("hijacking".toCharArray()));
    System.out.println(c("pneumonia".toCharArray()));
    System.out.println(c("klaxon".toCharArray()));
    System.out.println(c("perform".toCharArray()));
    System.out.println(c("learning".toCharArray()));
    System.out.println(c("dblacghmeifjk".toCharArray()));
  }
}