// mystk2.cpp -- implementation of the stack (by tsaiwn@csie.nctu.edu.tw)
#include "mystk2.h"
void MyStack::push(int x)
{
    stkptr++;
    data[stkptr] = x;
}  
int MyStack :: top(void)
{
    return data[stkptr];
}
//Actually,  pop( ) function is a void function in C++ STL
void MyStack ::pop(void)
{
    if(stkptr> -1) --stkptr;
}