public class Prac12 {

    /**
     * @pre     the sequence s is assumed to contain at least one negative number.
     * */
    public static int sequenceLength(int[] s)
    {
        int i;
        for (i = 0; i < s.length; i++)
        {
            if (s[i] >= 0)
            {
                System.out.println(i);
            }
        }
        return i;
    }

    public static void main(String[] args) {
        int[] s = {4, 5, 6, 7, -1};
        sequenceLength(s);
    }

}