Problem with push() in Stack using array

[sut]

As the program, stack should be overflow when pushing more than 5 data but overflow does not work till 7 data input.I could not find any error in my code.I need your help.

  #include <iostream>
#include <conio.h>
#include <stdlib.h>
class stack
{
	int stk[5];
	int top;
	public:
	stack()
	{
		top=-1;
	}
	void push (int x)
	{
			if (top >4)
			{
				cout<<"stack overflow";
				return;
			}
			
			stk[++top]=x;
			cout<<"inserted"<<x;
			
	}
	void pop()
	{
		if(top<0)
		{
			cout<<"stack underflow";
			return;
		}
		cout<<"deleted"<<stk[top--];
	}
	void display()
	{
		if(top<0)
		{
			cout<<"stack empty";
			return;
			
		}
		for(int i=top;i>=0;i--)
		{
			cout<<stk[i]<<" ";
		}
	}
	
	
};

void main()
{
	int ch;
	stack st;
	while(1)
	{
		cout<<"\n1.push 2.pop 3.display 4.exit\nEnter your choice";
		cin>>ch;
		switch(ch)
		{
			case 1:
			cout<<"enter the element ";
			cin>>ch;
			st.push(ch);
			break;
			case 2:
			st.pop();
			break;
			case 3:
			st.display();
			break;
			case 4:
			exit(0);
			
			
		}
	}
	return 0;
}