C++ program to count member function calls

/* C++ program to count member funtion calls */

#include<iostream>
using namespace std;

class A
 {
  int data;
  static int i,j;
  public:
  void input()
  {
  cout<<"enter num : ";
  cin>>data;
  i++;
  }
  void display()
  {
  cout<<"\nnum is "<<data<<endl;
  j++;
  }
  void count()
  {
  cout<<"\nInput calls = "<<i<<"\nDisplay calls = "<<j<<endl;
  }
 };
int A :: i=0;
int A :: j=0;

int main()
 {
  A A1;
  int c;
  do
  {
  cout<<"\n1.INPUT\n2.OUTPUT\n3.COUNT\n4.EXIT\nENTER CHOICE : ";
  cin>>c;
  switch(c)
  {
  case 1:
  A1.input();
  break;
case 2:
  A1.display();
  break;
case 3:
  A1.count();
  break;
default :
return 0;
  }
  }
  while(c);
  return 0;
 }