Termination Upon Esc

#include "iostream"
#include "conio.h"
using namespace std;
void main ()
{
    signed int a=0;
    do
    {
        a++;
        cout<<a<<endl;

    }
    while (a>-1);
    getch();
}

I want this loop program to terminate upon pressing esc key. How do I do that /prog/? Halp me pls.

>>11
FFS, just because it's NP complete doesn't mean it's impossible. It will only be pratcial for small cases (< size 50), but OP's program seems simple enough, so it should work.