#include <cmath>
#include <iostream>

struct Point {
  double x = 0.0, y = 0.0, z = 0.0;

  Point operator *(double a) const {
    return {x * a, y * a, z * a};
  }

  Point operator /(double a) const {
    return {x / a, y / a, z / a};
  }

  Point operator +(const Point& another) const {
    return {another.x + this->x, another.y + this->y, another.z + this->z};
  }
};

struct Segment {
  Point begin, end;
};

double FindDistanceBetweenPoints(const Point& point_1, const Point& point_2) {
  return std::sqrt(std::pow(point_1.x - point_2.x, 2) + std::pow(point_1.y - point_2.y, 2) + std::pow(point_1.z - point_2.z, 2));
}

double FindDistanceBetweenSegmentAndPoint(const Segment& segment, const Point& point, double eps) {
  Point right = segment.end;
  Point left = segment.begin;
  double dist_left = 0.0;
  double dist_right = 0.0;
  do {
    Point left_candidate = (left * 2 + right) / 3;
    Point right_candidate = (left + right * 2) / 3;
    dist_left = FindDistanceBetweenPoints(point, left_candidate);
    dist_right = FindDistanceBetweenPoints(point, right_candidate);
    if (dist_left < dist_right) {
      right = right_candidate;
    } else {
      left = left_candidate;
    }
  } while (FindDistanceBetweenPoints(left, right) > eps);

  return dist_left;
}

double FindDistanceBetweenSegments(const Segment& first, const Segment& second, double eps) {
  Point right = second.end;
  Point left = second.begin;
  double dist_left = 0.0;
  double dist_right = 0.0;
  do {
    Point left_candidate = (left * 2 + right) / 3;
    Point right_candidate = (left + right * 2) / 3;
    dist_left = FindDistanceBetweenSegmentAndPoint(first, left_candidate, eps);
    dist_right = FindDistanceBetweenSegmentAndPoint(first, right_candidate, eps);
    if (dist_left < dist_right) {
      right = right_candidate;
    } else {
      left = left_candidate;
    }
  } while (FindDistanceBetweenPoints(left, right) > eps);

  return dist_left;
}

int main() {
  double x, y, z;

  std::cin >> x >> y >> z;
  Point segment_begin = {x, y, z};
  std::cin >> x >> y >> z;
  Point segment_end = {x, y, z};
  Segment segment_1 = {segment_begin, segment_end};

  std::cin >> x >> y >> z;
  segment_begin = {x, y, z};
  std::cin >> x >> y >> z;
  segment_end = {x, y, z};
  Segment segment_2 = {segment_begin, segment_end};

  std::cout.precision(8);
  std::cout << std::fixed << FindDistanceBetweenSegments(segment_1, segment_2, 0.00000001);
  return 0;
}