please please please Need help urgently

[sonog4]

This is the code of my assignment programme problem is this it takes the inputs properly but close the cmd window without showing any result. Where i m making any mistake please mention?and correct the code please. please please please

#include <iostream.h>
using namespace std;
main()
{                                     //Initialization of veriables
      char grad;                     //to take inputs of grades A or B
      int tnos, ga, gb;              
      tnos = 1;                      //Total number of students
      ga = 0;                        //Total number of grad 'a'
      gb = 0;                        //Total number of grad 'b'
      do
      {
           cout<<"Enter the Grade of Student "<<tnos<<" :";    //to take inputs
                 cin>>grad;
                 if(grad=='a')            //to decide while the grade is 'a', 'b' or anyother
                 {
                         ga=ga+1;            //counter to count 'a' grades
                         tnos=tnos+1;
                         }
                 else if(grad=='b')
                 {
                              gb=gb+1;          //counter to count 'b' grades
                              tnos=tnos+1;
                              }
                 else
                 {
                     cout<<"Please enter only grads A or B:";
                     }
                     }
                     while(tnos<=10);               //maximum inputs to take or total number of students whos grades are required
                                {
                                     cout<<"Total A grades are : "<<ga;
                                     cout<<"Total B grades are : "<<gb;
                                     }
                                     
                                     //Now on the basis of total number of grades we shell show the status of a class.
                                     
                                     if(ga<=2)
                                     cout<<"Your class is Poor..!";
                                     else if(ga<=7)
                                     cout<<"Your class is Good..!";
                                     else
                                     cout<<"Your class is Brilliant..!";
                 }

[Paul McKenzie]

This is the code of my assignment programme problem is this it takes the inputs properly but close the cmd window without showing any result.

Run the program from the command-line.

Regards,

Paul McKenzie

[Morbane]

using namespace std;//before main

system("pause");//before return whatever

return whatever;