public class Test {
    public static void main(String[] args) {
        String time = "2359";
        System.out.println(getMinutes(time));
    }

    public static int getMinutes(String time) {
        if (time.length() != 4) {
            return -1;
        }
        int hour = Integer.parseInt(time.substring(0, 2));
        int minute = Integer.parseInt(time.substring(2));
        if (hour < 0 || hour > 23 || minute < 0 || minute > 59) {
            return -1;
        }
        return hour * 60 + minute;
    }
}