cant get this to run on my compiler, any idea of where im going wrong in my code here, any help would be so helpful

```
#define pi 3.1415926535897
#include<iostream>
#include<math.h>
using namespace std;
int main ()
{
double lat1=pi/180;
double long1=pi/180;
double lat2=pi/180;
double long2=pi/180; // initilaise values
double latz = 0;
double longz = 0;
double a = 0;
double c = 0;
double d = 0;
double x = 0;
double y = 0;
cout << "enter in radians " << endl;
cin >> lat1;
cin >> long1;
cin >> lat2;
cin >> long2;
latz = (lat2 - lat1);
longz = (long2 - long1);
cout << latz << endl;
cout << longz << endl;
a = sin(latz/2) * sin(latz/2) + cos(lat1) * cos(lat2)
* sin(longz/2) * sin(longz/2);
cout << " A is equal to: " << a << endl;
x = sqrt(a);
cout << x << endl;
y = sqrt(1-a);
cout << y << endl;
c = 2* atan2(x ,y);
cout << " C is equal to: " << c << endl;
d = 6371 * c; //greatcircle distance in km
cout << " and D is: " << d <<"km";
char in;
cin >> in;
}
```