Loops Practise

#include <iostream.h>
#include <conio.h>
int main ()
{
    clrscr ();
    long int start=0;
    long int last=0;
    long int a=0;
    cout <<"Enter The First Number: ";
    cin >> start;
    cout <<"\n Enter Second Number : ";
    cin >> last;
    for (int n=last;n>=start;n--)
    {
        if (a==0)
            a=last;
        last=last-1;
        a=a+last;
        n=last;
    }
    cout <<"\n Sum Of All Integers is = " <<a;
    getch();
    return 0;