Thread: Why does this program run?

I test for input to be of length 6, yet even if i enter 5 digits program continues to run. ?

public class Task1b {
 
    public static void main(String[] args) {
 
        String input;
        String nUsage;
        int[] d = new int[10];
 
        Scanner scan1 = new Scanner(System.in);
        Scanner scan2 = new Scanner(System.in);
 
        boolean isValid = true;
 
        // Request User Input
        System.out.println("Enter 6 digits: ");
        input = scan1.nextLine();
        System.out.println("How many codewords do you want to generate?");
        nUsage = scan2.nextLine();
 
        // Ensure input is of length: 6
        if (input.length() != 6) {
            System.out.println("Input must be 6 numbers!");
        }
        // Prompt for a valid input
        if (nUsage.length() == 0) {
            System.out.println("Please enter a valid number");
        }
        int n = Integer.parseInt(nUsage);
 
        if (n <= 0) {
            System.out.println("Please enter a valid number");
        }
        // Convert the String which stores the first 6 digits to an Integer
        int intBeginNumber = Integer.parseInt(input);
 
        while (n > 0) {
            isValid = true;
            String strGenerate = "";
            int tempNumber = intBeginNumber;
 
            // Set d [5],d[4],....d[0]
            for (int i = 0; i < 6; i++) {
                d[5 - i] = tempNumber % 10;
                tempNumber /= 10;
            }
 
            // d7 = (4 * d1 + 10 * d2 + 9 * d3 + 2 * d4 + d5 + 7 * d6) % 11;
            d[6] = (4 * d[0] + 10 * d[1] + 9 * d[2] + 2 * d[3] + d[4] + 7 * d[5]) % 11;
            // d8 = (7 * d1 + 8 * d2 + 7 * d3 + d4 + 9 * d5 + 6 * d6) % 11;
            d[7] = (7 * d[0] + 8 * d[1] + 7 * d[2] + d[3] + 9 * d[4] + 6 * d[5]) % 11;
            // d9 = (9 * d1 + d2 + 7 * d3 + 8 * d4 + 7 * d5 + 7 * d6) % 11;
            d[8] = (9 * d[0] + d[1] + 7 * d[2] + 8 * d[3] + 7 * d[4] + 7 * d[5]) % 11;
            // d10 = (d1 + 2 * d2 + 9 * d3 + 10 * d4 + 4 * d5 + d6) % 11;
            d[9] = (d[0] + 2 * d[1] + 9 * d[2] + 10 * d[3] + 4 * d[4] + d[5]) % 11;
 
            for (int i = 0; i < 10; i++) {
                if (d[i] == 10) {
                    // If i is equal to 10, then its an unusable number
                    isValid = false;
                    break;
                } else {
                    strGenerate = strGenerate.concat(Integer.toString(d[i]));
                }
            }
 
            if (isValid) {
                // Print out the generated number(s)
                System.out.println(strGenerate + " ");
 
                // Decrease number usage
                n--;
            }
 
            // Try next number
            intBeginNumber++;
        }
    }
}

You can test for the "length" of input. i.e. if input is 5 then loop only 5 times. If 4 then loop only 4. Assign the length a variable and test against that variable.