import java.util.*;

class Flight {
    public String tail_num;
    public boolean canceled;
    /* other fields from the real data intentionally omitted */

    public Flight(String tail_num, boolean canceled) {
        this.tail_num = tail_num;
        this.canceled = canceled;
    }
}

class OutputRow {
    public String tail_num;
    public int count;

    public OutputRow(String tail_num, int count) {
        this.tail_num = tail_num;
        this.count = count;
    }

    @Override
    public String toString() {
        return "(" + tail_num + ", " + count + ")";
    }
}

public class HW3 {
    public static List<OutputRow> problem3(List<Flight> flights) {
        // TODO: your code here
    }

    public static void main(String[] args) {
        List<Flight> mock_flights = new ArrayList<>();
        mock_flights.add(new Flight("N45517", true));
        mock_flights.add(new Flight("N80847", false));
        mock_flights.add(new Flight("N1358V", false));
        mock_flights.add(new Flight("N80847", true));
        mock_flights.add(new Flight("N719SJ", false));
        mock_flights.add(new Flight("N1358V", true));
        mock_flights.add(new Flight("N80847", false));

        List<OutputRow> output = problem3(mock_flights);
        for (OutputRow row : output) {
            System.out.println(row);
        }
    }
}

// Expected output:
// 
//     (N80847, 2)
//     (N719SJ, 1)
//     (N1358V, 1)
//
// (The two lines with count 1 may be printed in either order.)
//
// Your code will be tested on other data, so do not hard code the answer.