using System;

public class Program

{

    public static void Main()

    {   

        string n1,n2,n3;

        Console.WriteLine("enter binary no1 : ");

        n1=Console.ReadLine();

        Console.WriteLine("enter binary no2 :");

        n2=Console.ReadLine();

         int carry=0;

         n3= "";

        string sum = "";

           for(int i=(n1.Length)-1;i>=0;i--)

           {

               if(carry==0)

               {

                    if((n1[i]== '0')&&(n2[i]== '0'))

                      {

                          sum='0' + sum ;

                          carry=0;

                      }

                   else if((n1[i]== '0')&&(n2[i]== '1'))

                   {

                       sum='1'  + sum ;

                       carry=0;

                   }

                   else if(n1[i]== '1' &&n2[i]== '0')

                   {

                       sum='1'  + sum ;

                       carry=0;

                   }

                   else if(n1[i]=='1'&&n2[i]=='1')

                   {

                       sum='0'  + sum ;

                        carry=1;

                   }

               }   

              if(carry==1)

               {

                  if(n1[i]=='0'&&n2[i]=='0')

                      {

                          sum='1'  + sum ;

                          carry=0;

                      }

                  else if(n1[i]=='0'&&n2[i]=='1')

                   {

                       sum='0'  + sum ;

                       carry=1;

                   }

                  else if(n1[i]=='1'&&n2[i]=='0')

                   {

                       sum='0'  + sum ;

                       carry=1;

                   }

                  else if(n1[i]=='1'&&n2[i]=='1')

                   {

                       sum='1'  + sum ;

                        carry=1;

                   }

               }

               n3=sum;

               }

         Console.WriteLine("the binary no after addition is :"+sum);

         Console.WriteLine("the binary no after addition is :"+n3);

           }

    }

​