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 "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
template<class T>
using Table = vector<vector<T>>;
const ld eps=1e-9;

//// < "D:\D_Download\Visual Studio 2015\Projects\programing_contest_c++\Debug\a.txt"


#include <complex>

typedef long double ld;
typedef complex<ld> Point;
#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()


const ld pi = acos(-1.0);
const ld dtop = pi / 180.;
const ld ptod = 1. / dtop;

namespace std {
  bool operator<(const Point &lhs, const Point &rhs) {
    if (lhs.real() < rhs.real() - eps) return true;
    if (lhs.real() > rhs.real() + eps) return false;
    return lhs.imag() < rhs.imag();
  }
}

Point input_point() {
  ld x, y;
  cin >> x >> y;
  return Point(x, y);
}

bool eq(const ld a, const ld b) {
  return (abs(a - b) < eps);
}

ld dot(const Point& a, const Point& b) {
  return real(conj(a) * b);
}

ld cross(const Point& a, const Point& b) {
  return imag(conj(a) * b);
}

class Line {
public:
  Point a, b;
  Line() : a(Point(0, 0)), b(Point(0, 0)) {}
  Line(Point a, Point b) : a(a), b(b) {}
  Point operator[](const int _num)const {
    if (_num == 0)return a;
    else if (_num == 1)return b;
    else {
      assert(false);
      return Point();
    }
  }
};

class Circle {
public:
  Point p;
  ld r;
  Circle() : p(Point(0, 0)), r(0) {}
  Circle(Point p, ld r) : p(p), r(r) {}
};

// CCW
int ccw(const Point& a, const Point &b, const Point &c) {
  const Point nb(b - a);
  const Point nc(c - a);
  if (cross(nb, nc) > eps) return 1;   // a,b,c
  if (cross(nb, nc) < -eps) return -1; // a,
  if (dot(nb, nc) < 0) return 2;       //
  if (norm(nb) < norm(nc)) return -2;  // 
  return 0;                          
}


bool isis_ll(const Line& l, const Line& m) {
  return !eq(cross(l.b - l.a, m.b - m.a), 0);
}

bool isis_ls(const Line& l, const Line& s) {
  return isis_ll(l, s) &&
    (cross(l.b - l.a, s.a - l.a) * cross(l.b - l.a, s.b - l.a) < eps);
}
bool isis_ss(const Line& s, const Line& t) {
  return ccw(s.a, s.b, t.a) * ccw(s.a, s.b, t.b) <= 0 &&
    ccw(t.a, t.b, s.a) * ccw(t.a, t.b, s.b) <= 0;
}

bool isis_lp(const Line& l, const Point& p) {
  return (abs(cross(l.b - p, l.a - p)) < eps);
}

bool isis_sp(const Line& s, const Point& p) {
  return (abs(s.a - p) + abs(s.b - p) - abs(s.b - s.a) < eps);
}

Point proj(const Line &l, const Point& p) {
  ld t = dot(p - l.a, l.a - l.b) / norm(l.a - l.b);
  return l.a + t * (l.a - l.b);
}

Point is_ll(const Line &s, const Line& t) {
  Point sv = s.b - s.a, tv = t.b - t.a;
  assert(cross(sv, tv) != 0);
  return s.a + sv * cross(tv, t.a - s.a) / cross(tv, sv);
}
vector<Point> is_ll2(const Line &s, const Line& t) {
  Point sv = s.b - s.a, tv = t.b - t.a;
  if (cross(sv, tv) != 0)return vector<Point>(1, is_ll(s, t));
  else {
    vector<Point>ans;
    for (int k = 0; k < 2; ++k) {
      if (isis_sp(s, t[k]) && find(ans.begin(), ans.end(), t[k]) == ans.end())ans.push_back(t[k]);
      if (isis_sp(t, s[k]) && find(ans.begin(), ans.end(), s[k]) == ans.end())ans.push_back(s[k]);
    }
    return ans;
  }
}
Point is_ss(const Line &s, const Line& t) {
  if (isis_ss(s, t)) {
    for (int k = 0; k < 2; ++k) {
      for (int l = 0; l < 2; ++l) {
        if (s[k] == t[l])return s[k];
      }
    }
    return is_ll(s, t);
  }
  else {
    assert(false);
    return Point(0, 0);
  }
}
ld dist_lp(const Line& l, const Point& p) {
  return abs(p - proj(l, p));
}

ld dist_ll(const Line& l, const Line& m) {
  return isis_ll(l, m) ? 0 : dist_lp(l, m.a);
}

ld dist_ls(const Line& l, const Line& s) {
  return isis_ls(l, s) ? 0 : min(dist_lp(l, s.a), dist_lp(l, s.b));
}

ld dist_sp(const Line& s, const Point& p) {
  Point r = proj(s, p);
  return isis_sp(s, r) ? abs(r - p) : min(abs(s.a - p), abs(s.b - p));
}

ld dist_ss(const Line& s, const Line& t) {
  if (isis_ss(s, t)) return 0;
  return min({ dist_sp(s, t.a), dist_sp(s, t.b), dist_sp(t, s.a), dist_sp(t, s.b) });
}

Line bisection(const Line &s, const Line &t) {
  const Point laglanju(is_ll(s, t));
  const Point avec = !(abs(laglanju - s[0])<eps) ? s[0] - laglanju : s[1] - laglanju;
  const Point bvec = !(abs(laglanju - t[0])<eps) ? t[0] - laglanju : t[1] - laglanju;

  return Line(laglanju, laglanju + (abs(bvec)*avec + abs(avec)*bvec) / (abs(avec) + abs(bvec)));
}


Point  inner_center(const vector<Line>&ls) {
  vector<Point>vertics;
  for (int i = 0; i <static_cast<int>(ls.size()); ++i) {
    vertics.push_back(is_ll(ls[i], ls[(i + 1) % 3]));
  }
  if (vertics[0] == vertics[1] || vertics[1] == vertics[2] || vertics[2] == vertics[0])return vertics[0];
  Line bi1(bisection(Line(vertics[0], vertics[1]), Line(vertics[0], vertics[2])));
  Line bi2(bisection(Line(vertics[1], vertics[2]), Line(vertics[1], vertics[0])));
  if (bi1[0] == bi2[0])return bi1[0];
  else {
    return is_ll(bi1, bi2);
  }
}

vector<Point>  ex_center(const vector<Line>&ls) {
  vector<Point>vertics;
  for (int i = 0; i < static_cast<int>(ls.size()); ++i) {
    vertics.push_back(is_ll(ls[i], ls[(i + 1) % 3]));
  }
  if (abs(vertics[0] - vertics[1])<eps || abs(vertics[1] - vertics[2])<eps || (abs(vertics[2] - vertics[0])<eps))return vector<Point>();
  vector<Point>ecs;
  for (int i = 0; i < 3; ++i) {
    Line bi1(bisection(Line(vertics[i], vertics[i] * 2.0l - vertics[(i + 2) % 3]), Line(vertics[i], vertics[(i + 1) % 3])));
    Line bi2(bisection(Line(vertics[(i + 1) % 3], vertics[(i + 1) % 3] * 2.0l - vertics[(i + 2) % 3]), Line(vertics[(i + 1) % 3], vertics[i])));
    ecs.push_back(is_ll(bi1, bi2));
  }
  return ecs;
}


vector<Point>  same_dis(const vector<Line>&ls) {
  vector<Point>vertics;
  vertics.push_back(is_ll(ls[0], ls[2]));
  vertics.push_back(is_ll(ls[1], ls[2]));

  if (abs(vertics[0] - vertics[1]) < eps)return vector<Point>{vertics[0]};
  Line bis(bisection(ls[0], ls[1]));
  vector<Point>ecs;

  Line abi(bisection(Line(vertics[0], vertics[1]), ls[0]));
  ecs.push_back(is_ll(bis, abi));


  Line bbi(bisection(Line(vertics[0], 2.l*vertics[0] - vertics[1]), ls[0]));
  ecs.push_back(is_ll(bis, bbi));

  return ecs;
}
vector<Point> is_cc(const Circle& c1, const Circle& c2) {
  vector<Point> res;
  ld d = abs(c1.p - c2.p);
  ld rc = (d * d + c1.r * c1.r - c2.r * c2.r) / (2 * d);
  ld dfr = c1.r * c1.r - rc * rc;
  if (abs(dfr) < eps) dfr = 0.0;
  else if (dfr < 0.0) return res; // no intersection
  ld rs = sqrt(dfr);
  Point diff = (c2.p - c1.p) / d;
  res.push_back(c1.p + diff * Point(rc, rs));
  if (dfr != 0.0) res.push_back(c1.p + diff * Point(rc, -rs));
  return res;
}

int is_in_circle(const Circle &cir, const  Point& p) {
  ld dis = abs(cir.p - p);
  if (dis > cir.r + eps)return 0;
  else if (dis < cir.r - eps)return 2;
  else return 1;
}
int circle_in_circle(const Circle &lc, const  Circle&rc) {
  ld dis = abs(lc.p - rc.p);
  if (dis < rc.r - lc.r - eps)return 2;
  else if (dis>rc.r - lc.r + eps)return 0;
  else return 1;
}

vector<Point> is_lc(const Circle& c, const Line& l) {
  vector<Point> res;
  ld d = dist_lp(l, c.p);
  if (d < c.r + eps) {
    ld len = (d > c.r) ? 0.0 : sqrt(c.r * c.r - d * d); //safety;
    Point nor = (l.a - l.b) / abs(l.a - l.b);
    res.push_back(proj(l, c.p) + len * nor);
    res.push_back(proj(l, c.p) - len * nor);
  }
  return res;
}
vector<Point> is_sc(const Circle& c, const Line& l) {
  vector<Point> v = is_lc(c, l), res;
  for (Point p : v)
    if (isis_sp(l, p)) res.push_back(p);
  return res;
}

vector<Line> tangent_cp(const Circle& c, const Point& p) {
  vector<Line> ret;
  Point v = c.p - p;
  ld d = abs(v);
  ld l = sqrt(norm(v) - c.r * c.r);
  if (isnan(l)) { return ret; }
  Point v1 = v * Point(l / d, c.r / d);
  Point v2 = v * Point(l / d, -c.r / d);
  ret.push_back(Line(p, p + v1));
  if (l < eps) return ret;
  ret.push_back(Line(p, p + v2));
  return ret;
}

vector<Line> tangent_cc(const Circle& c1, const Circle& c2) {
  vector<Line> ret;
  if (abs(c1.p - c2.p) - (c1.r + c2.r) > -eps) {
    Point center = (c1.p * c2.r + c2.p * c1.r) / (c1.r + c2.r);
    ret = tangent_cp(c1, center);
  }
  if (abs(c1.r - c2.r) > eps) {
    Point out = (-c1.p * c2.r + c2.p * c1.r) / (c1.r - c2.r);
    vector<Line> nret = tangent_cp(c1, out);
    ret.insert(ret.end(), ALL(nret));
  }
  else {
    Point v = c2.p - c1.p;
    v /= abs(v);
    Point q1 = c1.p + v * Point(0, 1) * c1.r;
    Point q2 = c1.p + v * Point(0, -1) * c1.r;
    ret.push_back(Line(q1, q1 + v));
    ret.push_back(Line(q2, q2 + v));
  }
  return ret;
}
ld two_circle_area(const Circle&l, const Circle&r) {
  ld dis = abs(l.p - r.p);
  if (dis > l.r + r.r)return 0;
  else if (dis + r.r < l.r) {
    return r.r*r.r*pi;
  }
  else if (dis + l.r < r.r) {
    return l.r*l.r*pi;
  }
  else {
    ld ans = (l.r)*(l.r)*acos((dis*dis + l.r*l.r - r.r*r.r) / (2 * dis*l.r)) +
      (r.r)*(r.r)*acos((dis*dis + r.r*r.r - l.r*l.r) / (2 * dis*r.r)) -
      sqrt(4 * dis*dis*l.r*l.r - (dis*dis + l.r*l.r - r.r*r.r)*(dis*dis + l.r*l.r - r.r*r.r)) / 2;
    return ans;
  }

}


typedef vector<Point> Polygon;

ld area(const Polygon &p) {
  ld res = 0;
  int n = p.size();
  REP(j, n) res += cross(p[j], p[(j + 1) % n]);
  return res / 2;
}

bool is_counter_clockwise(const Polygon &poly) {
  ld angle = 0;
  int n = poly.size();
  REP(i, n) {
    Point a = poly[i], b = poly[(i + 1) % n], c = poly[(i + 2) % n];
    angle += arg((c - b) / (b - a));
  }
  return angle > eps;
}

int is_in_polygon(const Polygon &poly, const  Point& p) {
  ld angle = 0;
  int n = poly.size();
  REP(i, n) {
    Point a = poly[i], b = poly[(i + 1) % n];
    if (isis_sp(Line(a, b), p)) return 1;
    angle += arg((b - p) / (a - p));
  }
  return eq(angle, 0) ? 0 : 2;
}
enum { OUT, ON, IN };
int convex_contains(const Polygon &P, const Point &p) {
  const int n = P.size();
  Point g = (P[0] + P[n / 3] + P[2 * n / 3]) / 3.0l; // inner-point
  int a = 0, b = n;
  while (a + 1 < b) { // invariant: c is in fan g-P[a]-P[b]
    int c = (a + b) / 2;
    if (cross(P[a] - g, P[c] - g) > 0) { // angle < 180 deg
      if (cross(P[a] - g, p - g) > 0 && cross(P[c] - g, p - g) < 0) b = c;
      else                                                  a = c;
    }
    else {
      if (cross(P[a] - g, p - g) < 0 && cross(P[c] - g, p - g) > 0) a = c;
      else                                                  b = c;
    }
  }
  b %= n;
  if (cross(P[a] - p, P[b] - p) < 0) return 0;
  if (cross(P[a] - p, P[b] - p) > 0) return 2;
  return 1;
}

Polygon convex_hull(vector<Point> ps) {
  int n = ps.size();
  int k = 0;
  sort(ps.begin(), ps.end());
  Polygon ch(2 * n);
  for (int i = 0; i < n; ch[k++] = ps[i++])
    while (k >= 2 && ccw(ch[k - 2], ch[k - 1], ps[i]) <= 0) --k;
  for (int i = n - 2, t = k + 1; i >= 0; ch[k++] = ps[i--])
    while (k >= t && ccw(ch[k - 2], ch[k - 1], ps[i]) <= 0) --k;
  ch.resize(k - 1);
  return ch;
}



vector<Polygon> convex_cut(const Polygon &ps, const Line& l) {
  int n = ps.size();
  Polygon Q;
  Polygon R;
  REP(i, n) {
    Point A = ps[i], B = ps[(i + 1) % n];
    Line m = Line(A, B);
    if (ccw(l.a, l.b, A) != -1) Q.push_back(A);
    if (ccw(l.a, l.b, A) != 1) R.push_back(A);
    if (ccw(l.a, l.b, A) * ccw(l.a, l.b, B) < 0 && isis_ll(l, m)) {
      Q.push_back(is_ll(l, m));
      R.push_back(is_ll(l, m));
    }
  }
  const vector<Polygon>polys{ Q,R };
  return polys;
}


void add_point(vector<Point> &ps, const Point p) {
  for (Point q : ps) if (abs(q - p) < eps) return;
  ps.push_back(p);
}

typedef int Weight;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(int src, int dst, Weight weight) :
    src(src), dst(dst), weight(weight) { }
};

typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

void add_edge(Graph &g, const int from, const int to, const Weight weight) {
  g[from].push_back(Edge{ from, to, weight });
}

Graph segment_arrangement(const vector<Line> &s, const vector<Point> &p) {
  int n = p.size(), m = s.size();
  Graph g(n);
  REP(i, m) {
    vector<pair<ld, int>> vec;
    REP(j, n) if (isis_sp(s[i], p[j]))
      vec.emplace_back(abs(s[i].a - p[j]), j);
    sort(ALL(vec));
    REP(j, vec.size() - 1) {
      int from = vec[j].second, to = vec[j + 1].second;
      add_edge(g, from, to, static_cast<Weight>(abs(p[from] - p[to])));
    }
  }
  return g;
}
Graph sennbunn_arrangement(const vector<Line>&s) {
  vector<Point>crss;
  for (int i = 0; i < static_cast<int>(s.size()); ++i) {
    for (int j = i + 1; j < static_cast<int>(s.size()); ++j) {
      if (isis_ss(s[i], s[j])) {
        crss.push_back(is_ll(s[i], s[j]));
      }
    }
  }
  for (int i = 0; i <static_cast<int>(s.size()); ++i) {
    crss.push_back(s[i][0]);
    crss.push_back(s[i][1]);
  }
  return segment_arrangement(s, crss);
}

//Graph circle_arrangement(const vector<Circle> &c, const vector<Point> &p) {
//	int n = p.size(), m = c.size();
//	Graph g(n);
//	REP(i, m) {
//		vector<pair<ld, int>> vec;
//		REP(j, n) if (abs(abs(c[i].p - p[j]) - c[i].r) < eps)
//			vec.emplace_back(arg(c[i].p - p[j]), j);
//		sort(ALL(vec));
//		REP(j, vec.size() - 1) {
//			int from = vec[j].second, to = vec[j + 1].second;
//			ld angle = vec[j + 1].first - vec[j].first;
//			add_edge(g, from, to, static_cast<Weight>(angle * c[i].r));
//		}
//		if (vec.size() >= 2) {
//			int from = vec.back().second, to = vec.front().first;
//			ld angle = vec.front().first - vec.back().first;
//			add_edge(g, from, to, static_cast<Weight>(angle * c[i].r));
//		}
//	}
//	return g;
//}


/* ????????°?????? */

// ?????????????????¢?????¢??¬??????????????????????????????????????°???????????????
// ?????´?????????????¨?????????§????????´????????????????¨?????????§???????????????
// ?????° polygon ??????vector<int> ??§??¨?????????????§???¢???????????§?????????
// vector<int> ??§??¨????????? ????§???¢???i???????????????????????????????????????p????????????????????§?????????
vector<vector<int>> polygon;
vector<int> seg2p[1024][1024];

//Graph dual_graph(const vector<Line> &s, const vector<Point> &p) {
//	int N = p.size();
//	polygon.clear();
//	REP(i, 1024) REP(j, 1024) seg2p[i][j].clear();
//	vector<vector<tuple<ld, int, bool>>> tup(N);
//	REP(i, s.size()) {
//		int a = -1, b = -1;
//		REP(j, N) if (abs(s[i].a - p[j]) < eps) a = j;
//		REP(j, N) if (abs(s[i].b - p[j]) < eps) b = j;
//		assert(a >= 0 && b >= 0);
//		tup[a].emplace_back(arg(s[i].b - s[i].a), b, false);
//		tup[b].emplace_back(arg(s[i].a - s[i].b), a, false);
//	}
//	REP(i, N) sort(ALL(tup[i]));
//	REP(i, N) {
//		REP(j, tup[i].size()) {
//			ld angle; int pos = j, from = i, to; bool flag;
//			tie(angle, to, flag) = tup[i][j];
//			if (flag) continue;
//			vector<int> ps;
//			while (!flag) {
//				ps.push_back(from);
//				get<2>(tup[from][pos]) = true;
//				seg2p[from][to].push_back(polygon.size());
//				seg2p[to][from].push_back(polygon.size());
//				angle += pi + eps;
//				if (angle > pi) angle -= 2 * pi;
//				auto it = lower_bound(ALL(tup[to]), make_tuple(angle, 0, false));
//				if (it == tup[to].end()) it = tup[to].begin();
//				from = to; tie(angle, to, flag) = *it;
//				pos = it - tup[from].begin();
//			}
//			polygon.push_back(ps);
//		}
//	}
//	Graph g(polygon.size());
//	REP(i, N) REP(j, i) {
//		if (seg2p[i][j].size() == 2) {
//			int from = seg2p[i][j][0], to = seg2p[i][j][1];
//			g[from].push_back(Edge{ from, to });
//			g[to].push_back(Edge{ to, from });
//		}
//	}
//	return g;
//}




int main() {
  
  int N; cin >> N;
  vector<Point>ps;
  for (int i = 0; i < N; ++i) {
    int x, y; cin >> x >> y;
    Point p(x, y);
    ps.push_back(p);
  }

  Point center = (ps[0] + ps[1]) / 2.l;
  bool ok = true;
  if (N % 2) {
    ok = false;
  }
  else {
    center = (ps[0] + ps[N/2]) / 2.l;
    
    for (int i = 0; i < N / 2; ++i) {
      Point kouho = (ps[ i] + ps[(i + N/2)%N]) / 2.l;
      if (abs(center - kouho) > eps)ok = false;
    }
  }
  if (ok)cout << setprecision(22) << fixed << center.real() << " " << center.imag() << endl;
  else cout << "NA" << endl;
  return 0;
}