Fourth Point !!
#include <iostream>
using namespace std;
class point {
public:
double x;
double y;
bool equals(const point &p) {
if (p.x == x && p.y == y)
return true;
return false;
}
};
int main() {
point a, b, c, d;
while (cin >> a.x >> a.y >> b.x >> b.y >> c.x >> c.y >> d.x >> d.y) {
point e;
if (a.equals(c)) {
swap(a, b);
} else if (a.equals(d)) {
swap(a, b);
swap(c, d);
} else if (b.equals(d)) {
swap(c, d);
}
e.x = d.x + a.x - b.x;
e.y = a.y + d.y - b.y;
printf("%.3f %.3f\n", e.x, e.y);
}
return 0;
}