Problem: Gena doesn't like geometry, so he asks you to solve this problem for him.

A rectangle with sides parallel to coordinate axes contains n dots. Let's consider some point of the plane. Let's count the distances from this point to the given n points. Let's sort these numbers in the non-decreasing order. We'll call the beauty of the point the second element of this array. If there are two mimimum elements in this array, the beaty will be equal to this minimum.

Find the maximum beauty of a point inside the given rectangle.

Input

The first line contains three integers w, h, n (1 ≤ w, h ≤ 106, 2 ≤ n ≤ 1000) — the lengths of the rectangle sides and the number of points. Next n lines contain two integers xi, yi (0 ≤ xi ≤ w, 0 ≤ yi ≤ h) each — the coordinates of a point. It is possible that it will be coincident points.

Output

Print a single number — the maximum beauty of a point with the absolute or relative error of at most 10 - 9.

Examples

Input

5 5 4
0 0
5 0
0 5
5 5


Output

4.99999999941792340


Input

5 5 3
4 0
2 5
4 1


Output

5.65685424744772010

Note

The point which beauty we need to find must have coordinates (x, y), where 0 ≤ x ≤ w, 0 ≤ y ≤ h. Some of the n points can coincide.

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1015;
const double inf = 1500000;
const int MyConst = 40;
const double eps = 1e-9;
const double pi = acos(-1);
struct point {
  double x, y;
};
struct AnglePoint {
  double ang;
  int ind;
  bool open;
  AnglePoint() {}
  AnglePoint(double _ang, int _ind, bool _open) {
    ang = _ang;
    ind = _ind;
    open = _open;
    if (ang > 2 * pi) ang -= 2 * pi;
    if (ang < 0) ang += 2 * pi;
  }
};
bool operator==(point A, point B) { return (A.x == B.x && A.y == B.y); }
bool compare(AnglePoint X, AnglePoint Y) {
  if (!(X.open ^ Y.open)) return X.ang < Y.ang;
  if (Y.ang - X.ang > eps) return true;
  if (X.ang - Y.ang > eps) return false;
  if (!X.open)
    return true;
  else
    return false;
}
int N;
double W, H;
point p[MAXN];
AnglePoint Angle[2 * MAXN];
double dist(point A, point B) {
  double dx = A.x - B.x;
  double dy = A.y - B.y;
  return sqrt((dx * dx) + (dy * dy));
}
double GetAngle(point A, point B) {
  double trig = (B.x - A.x) / (dist(A, B));
  if (B.y - A.y < 0)
    return (2 * pi - acos(trig));
  else
    return acos(trig);
}
double GetTAngle(double d, double R) { return acos(d / (2 * R)); }
double GetLAngle(double d, double R) { return acos(d / R); }
bool Check(point A, double R) {
  int total = 0;
  int inside = 0;
  for (int i = 1; i <= N; i++) {
    point B = p[i];
    if (A == B) continue;
    if (dist(A, B) > 2 * R) continue;
    double alfa = atan2(B.y - A.y, B.x - A.x);
    double beta = GetTAngle(dist(A, B), R);
    total++;
    Angle[total] = AnglePoint(alfa - beta, total, true);
    total++;
    Angle[total] = AnglePoint(alfa + beta, total, false);
    if (Angle[total].ang < Angle[total - 1].ang) inside++;
  }
  if (A.x < R) {
    double beta = GetLAngle(A.x, R);
    for (int i = 1; i <= 2; i++) {
      total++;
      Angle[total] = AnglePoint(pi - beta, total, true);
      total++;
      Angle[total] = AnglePoint(pi + beta, total, false);
    }
  }
  if (W - A.x < R) {
    double beta = GetLAngle(W - A.x, R);
    for (int i = 1; i <= 2; i++) {
      total++;
      Angle[total] = AnglePoint(0 - beta, total, true);
      total++;
      Angle[total] = AnglePoint(0 + beta, total, false);
      inside++;
    }
  }
  if (A.y < R) {
    double beta = GetLAngle(A.y, R);
    for (int i = 1; i <= 2; i++) {
      total++;
      Angle[total] = AnglePoint(1.5 * pi - beta, total, true);
      total++;
      Angle[total] = AnglePoint(1.5 * pi + beta, total, false);
    }
  }
  if (H - A.y < R) {
    double beta = GetLAngle(H - A.y, R);
    for (int i = 1; i <= 2; i++) {
      total++;
      Angle[total] = AnglePoint(0.5 * pi - beta, total, true);
      total++;
      Angle[total] = AnglePoint(0.5 * pi + beta, total, false);
    }
  }
  if (inside < 2) return true;
  sort(Angle + 1, Angle + total + 1, compare);
  for (int i = 1; i <= total; i++) {
    if (Angle[i].open)
      inside++;
    else
      inside--;
    if (inside < 2) return true;
  }
  return false;
}
int main() {
  cout << fixed << setprecision(15);
  scanf("%lf", &W);
  scanf("%lf", &H);
  scanf("%d", &N);
  for (int i = 1; i <= N; i++) {
    scanf("%lf %lf", &p[i].x, &p[i].y);
  }
  random_shuffle(p + 1, p + N + 1);
  double l = eps, r = min(inf, W + H);
  for (int i = 1; i <= N; i++) {
    if (!Check(p[i], l + l * eps)) continue;
    for (int iterations = 1; iterations <= MyConst; iterations++) {
      double R = (l + r) / 2;
      if (Check(p[i], R))
        l = R;
      else
        r = R;
    }
    r = min(inf, W + H);
  }
  cout << l << endl;
  return 0;
}