class Airport {
        public final String name;
        public final String arrivalStringTime;
        public final int arrivalTime;
        Airport(String name, String arrivalStringTime) {
            this.name = name;
            this.arrivalStringTime = arrivalStringTime;
            this.arrivalTime = getTime(arrivalStringTime);
        }
    }
    String flightPlan(String[][] times, String source, String dest) {
        Map<String, List<String[]>> flights = new HashMap<>();
        for (String[] flight : times) {
            flights.putIfAbsent(flight[0], new ArrayList<>());
            flights.putIfAbsent(flight[1], new ArrayList<>());
            flights.get(flight[0]).add(flight);
        }
        if (!flights.containsKey(source)) return "-1";
        PriorityQueue<Airport> queue = new PriorityQueue<>(Comparator.comparingInt(air -> air.arrivalTime));
        queue.add(new Airport(source, "00:00"));
        while (!queue.isEmpty()) {
            Airport node = queue.remove();
            if (node.name.equalsIgnoreCase(dest)) return node.arrivalStringTime;
            for (String[] flight : flights.get(node.name)) {
                if (node.arrivalTime+60 > getTime(flight[2])) continue;
                queue.add(new Airport(flight[1], flight[3]));
            }
        }
        return "-1";
    }

    private int getTime(String time) {
        return Integer.parseInt(time.substring(0,time.indexOf(':'))) * 60 + Integer.parseInt(time.substring(time.indexOf(':')+1));
    }