Problem: You are given two circles. Find the area of their intersection.

Input

The first line contains three integers x1, y1, r1 ( - 109 ≤ x1, y1 ≤ 109, 1 ≤ r1 ≤ 109) — the position of the center and the radius of the first circle.

The second line contains three integers x2, y2, r2 ( - 109 ≤ x2, y2 ≤ 109, 1 ≤ r2 ≤ 109) — the position of the center and the radius of the second circle.

Output

Print the area of the intersection of the circles. The answer will be considered correct if the absolute or relative error doesn't exceed 10 - 6.

Examples

Input

0 0 4
6 0 4


Output

7.25298806364175601379


Input

0 0 5
11 0 5


Output

0.00000000000000000000

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
const long double PI = 4.0L * atan2(1.0L, 1.0L);
long double areaOfCirclesIntersection(long double x0, long double y0,
                                      long double r0, long double x1,
                                      long double y1, long double r1) {
  long double rr0 = r0 * r0;
  long double rr1 = r1 * r1;
  long double d = sqrtl((x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0));
  if (d > r1 + r0) return 0;
  if (d <= fabs(r0 - r1) + 1e-9L && r0 >= r1 - 1e-9L) return PI * rr1;
  if (d <= fabs(r0 - r1) + 1e-9L && r0 < r1 - 1e-9L) return PI * rr0;
  long double phi = (acosl((rr0 + (d * d) - rr1) / (2L * r0 * d))) * 2L;
  long double theta = (acosl((rr1 + (d * d) - rr0) / (2L * r1 * d))) * 2L;
  long double area1 = 0.5L * theta * rr1 - 0.5L * rr1 * sinl(theta);
  long double area2 = 0.5L * phi * rr0 - 0.5L * rr0 * sinl(phi);
  return area1 + area2;
}
int main() {
  long double x1, y1, x2, y2, r, R;
  cin >> x1 >> y1 >> r >> x2 >> y2 >> R;
  cout << setprecision(11) << fixed
       << areaOfCirclesIntersection(x1, y1, r, x2, y2, R) << endl;
  return 0;
}