Scanner sc = new Scanner(System.in);
    String inputString = sc.nextLine();
    int length = sc.nextInt();
    String smallest="";
    String largest="";
    for(int i = 0;i<=inputString.length()-length;i++){
        String subString = inputString.substring(i,i+length);
        if(i == 0){
            smallest = subString;
        }
        if(subString.compareTo(largest)>0){
            largest = subString;
        }else if(subString.compareTo(smallest)<0)
            smallest = subString;
    }
    System.out.println(smallest);
    System.out.println(largest);

}

// Assign the string we want to process to a variable
inputStr = "welcometojava"
// define and array for each sub-string.
String[] substrs = new string[input.length()-2];
// Fill our container by iterating from 0 up through the place of the last sub string.
for(int i = 0; i < inputStr.length()-2; i++){
    // assign array members sub strings from input string for each starting position
    substrs[i] = inputStr.substring(i,i+3);
}
// Sort and print your results.
Arrays.sort(substrs);
for(int i = 0; i < args.length; i++)
    System.out.println(substrs[i]);