Problem: A convex polygon consisting of N vertices is given. The coordinates of each vertex are represented counterclockwise by (X1, Y1), (X2, Y2), ……, (XN, YN). No matter what straight line passes through the point P, find the coordinates of the point P so that the areas of the two convex polygons obtained after cutting are equal.

Constraints

* All inputs are integers

* 3 ≤ N ≤ 50

* 0 ≤ | Xi |, | Yi | ≤ 1000000

* The input polygon is a simple convex polygon.

* The output must satisfy max (| X-cX |, | Y-cY |) ≤ 0.0001 when the output coordinates are (X, Y) and the exact solution is (cX, cY).

Input

The input is given in the following format.

> N
> X1 Y1
> X2 Y2
> ……
> XN YN
>

Output

If there is a point that satisfies the condition of the problem statement, the coordinates of that point

> X Y
>

Output in the format of. If the point does not exist, output "NA" on one line.

Examples

Input

4
100 100
0 100
0 0
100 0


Output

50.00000 50.00000


Input

3
100 100
0 100
0 0


Output

NA

Solution (in CPP):

Solution:
#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdlib>
using namespace std;

/**************************************************************/

#define EPS (1e-10)
#define equals(a, b) (fabs((a) - (b)) < EPS)
#define PI acos(-1)
#define rad(t) double(t)*PI/180.0

// ???
class Point {
public:
	double x, y;

	Point(double x = 0.0, double y = 0.0) : x(x), y(y) {}

	Point operator + (Point p) {
		return Point(x + p.x, y + p.y);
	}
	Point operator - (Point p) {
		return Point(x - p.x, y - p.y);
	}
	Point operator * (double c) {
		return Point(c * x, c * y);
	}
	Point operator / (double c) {
		return Point(x / c, y / c);
	}
	bool operator < (const Point &p) const {
		return (x != p.x ? x < p.x : y < p.y);
	}
	bool operator == (const Point &p) const {
		return (fabs(x - p.x) < EPS && fabs(y - p.y) < EPS);
	}
	bool operator != (const Point &p) const {
		return (fabs(x - p.x) > EPS || fabs(y - p.y) > EPS);
	}

	// ?????????
	double norm() {
		return (x * x + y * y);
	}
	// ??§??????
	double abs() {
		return sqrt(norm());
	}
};

// ????????????
typedef Point Vector;

// ??????
double dot(Vector a, Vector b) {
	return (a.x * b.x + a.y * b.y);
}

// ??????
double cross(Vector a, Vector b) {
	return (a.x * b.y - a.y * b.x);
}

// ?????????
double norm(Vector a) {
	return (a.x * a.x + a.y * a.y);
}

// ??§??????
double abs(Vector a) {
	return sqrt(norm(a));
}

// ??????
class Segment {
public:
	Point p1, p2;

	Segment(Point p1 = Point(), Point p2 = Point()) : p1(p1), p2(p2) {}
};

// ??????(Parallel)????????????
bool isParal(Vector a, Vector b) {
	return equals(cross(a, b), 0.0);
}

bool isParal(Point a1, Point a2, Point b1, Point b2) {
	return isParal(a1 - a2, b1 - b2);
}

// ?????????????????????????????????!!
bool isParal(Segment s1, Segment s2) {
	return equals(cross(s1.p2 - s1.p1, s2.p2 - s2.p1), 0.0);
}

// ?????¨???????????¢
double distP(Point a, Point b) {
	return (a - b).abs();
}

int n;
vector<Point> v;

int main(void) {
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	cin >> n;
	v.resize(n);
	for (int i = 0; i < n; ++i) {
		cin >> v[i].x >> v[i].y;
	}
	if (n % 2) {
		cout << "NA" << endl;
		return 0;
	}

	for (int i = 0; i < n / 2; ++i) {
		Segment s(v[i], v[i+1]), t(v[(n/2+i)%n], v[(n/2+i+1)%n]);
		
		// ????????´????????¨????????§???????????????????????°????????°???????§°
		if (!isParal(s, t) || (s.p2 - s.p1).norm() != (t.p2 - t.p1).norm()) {
			cout << "NA" << endl;
			return 0;
		}
	}
	
	// ????§°???????????????????±???????
	Point ans((v[0].x + v[n/2].x)/2, (v[0].y + v[n/2].y)/2);
	
	cout << fixed;
	cout.precision(10);
	cout << ans.x << " " << ans.y << endl;
	
	return 0;
}