stack inside class problem

[Joe101]

Hi,
Below is the header file a Palindrome class that I'm writing. Could someone please tell me what syntax I need to employ to be able to include and use a stack. I get the following error message

"Expected ; before token <" on the line where I try to create the empty stack s.

#include <stack>

#ifndef PALINDROME_H_INCLUDED
#define PALINDROME_H_INCLUDED

class Palindrome{

public:
bool isPalindrome(int n);

private:
stack<int> s;
int num;

};

[helios]

std::stack<int> s;

[Joe101]

thanks so much!