what is wrong with this program

import java.io.*;

class Distance { 
    int feet;
    int inch;
    DataInputStream ob = new DataInputStream(System.in);
    void read()throws Exception { 
        System.out.println("Enter distance in feet and inches "); 
        feet=Integer.parseInt(ob.readLine());
        inch=Integer.parseInt(ob.readLine()); 
        } void distanceDisplay() { 
            System.out.println("Distance in feet "+feet); 
            System.out.println("Distance in inches "+inch); 
            }
            void add(Distance d1,Distance d2) { 
                int f,i;
                feet=d1.feet + d2.feet;
                inch=d1.inch + d2.inch;
                if(inch>=12) { 
                    f=inch/12; 
                    i=inch%12;
                    feet=feet+f;
                    inch=i;
                    } 
                    }
                    public static void main(String[] args) throws Exception {

                        Distance d1 = new Distance();
                        Distance d2 = new Distance();
                        Distance d3 = new Distance();
                        d1.read();
                        d2.read();
                        d3.add(d1,d2); 
                        d3.distanceDisplay(); 
                        } 
                        }