// Class Angle is used to store an angle in degrees and minutes, as in "29
// degrees and 35 minutes."
public class Angle implements Comparable<Angle> {
    private int degrees;
    private int minutes;
    
    // pre: minutes <= 59 and minutes >= 0 and degrees >= 0
    //    (throws IllegalArgumentException if not true)
    public Angle(int degrees, int minutes) {
        if (degrees < 0 || minutes < 0 || minutes >= 60) {
            throw new IllegalArgumentException();
        }
        this.degrees = degrees;
        this.minutes = minutes;
    }
    
    // post: returns a String representation of this angle as in "29d 35m"
    public String toString() {
        return degrees + "d " + minutes + "m";
    }
    
    // post: returns a new angle that represents the sum of this angle and the
    //     given angle
    public Angle add(Angle other) {
        int d = other.degrees + this.degrees;
        int m = other.minutes + this.minutes;
        if (m >= 60) {
            m -= 60;
            d += 1;
        }
        return new Angle(d, m);
    }
    
    // post: returns a negative if this angle less than the other, 0 if this
    //       angle equals the other, a positive if this angle greater than the
    //       other (ordered by degrees first, then by minutes)
    public int compareTo(Angle other) {
        if (this.degrees == other.degrees) {
            return this.minutes - other.minutes;
        } else {
            return this.degrees - other.degrees;
        }
    }
}