#include <vector>
#include <iostream>
#include <fstream>
#include <set>
#include <vector>
#include <string>
#include <queue>
#include <deque>
#include <ctime>
#include <algorithm>
#include <stdio.h>
#pragma warning(disable:4996)

using namespace std;

class mark
{
public:
	bool marked;
	int from, flow;
	mark()
	{
		marked = false;
	}

	void set(int from, int flow)
	{
		marked = true;
		this->flow = flow;
		this->from = from;
	}
};

int first_team[43];
int second_team[43];
int from[89];
int c[89][89]; // 0 - s, 1 - 43 первый отдел, 44 - 86 - второй отдел, 87 - для незаселенных, 88 - t
int f[89][89];
double sourceP[89][89];
double p[89][89];
double D[89];
mark marks[89];

int module(int a, int b)
{
	return a > b ? a - b : b - a;
}

bool bfs()
{
	queue <int> que;
	marks[0].set(-1, INT32_MAX);
	que.push(0);
	for (int i = 1; i < 89; i++)
		marks[i].marked = false;
	while (!que.empty())
	{
		for (int i = 0; i < 89; i++)
		{
			if (!marks[i].marked && c[que.front()][i] - f[que.front()][i] > 0)
			{
				marks[i].set(que.front(), min(c[que.front()][i] - f[que.front()][i], marks[que.front()].flow));
				que.push(i);
			}
		}
		if (marks[88].marked)
			return true;
		que.pop();
	}
	return false;
}

void fill(int diff)
{
	for (int i = 0; i < 89; i++)
		for (int g = 0; g < 89; g++)
			c[i][g] = 0;
	for (int i = 0; i < 43; i++)
	{
		if (first_team[i])
			c[0][i + 1] = first_team[i];
	}
	for (int i = 0; i < 43; i++)
		if (first_team[i])
		{
			for (int g = 0; g < 43; g++)
				if (second_team[g])
				{
					c[i + 1][g + 44] = min(first_team[i], second_team[g]);
				}
			c[i + 1][87] = min(first_team[i], diff);
		}
	for (int i = 0; i < 43; i++)
	{
		if (second_team[i])
			c[i + 44][88] = second_team[i];
	}
	c[87][88] = diff;
}

pair <int, int> dataRead()
{
	for (int i = 0; i < 43; i++)
	{
		first_team[i] = 0;
		second_team[i] = 0;
	}
	FILE * file = fopen("input.txt", "r");
	char symbol;
	int value, count1 = 0, count2 = 0;
	do
	{
		fscanf(file, "%d", &value);
		first_team[value - 18]++;
		count1++;
		symbol = fgetc(file);
	} while (symbol != 10);
	while (fscanf(file, "%d", &value) != EOF)
	{
		second_team[value - 18]++;
		count2++;
	}
	return make_pair(count1, count2);
}

void fillSource()
{
	for (int i = 0; i < 89; i++)
		for (int g = 0; g < 89; g++)
			sourceP[i][g] = 0;
	for (int i = 0; i < 43; i++)
	{
		for (int g = 0; g < 43; g++)
			sourceP[i + 1][g + 44] = module(i, g);
		sourceP[i + 1][87] = double(i) / 2 + 9;
	}
}

void fillP()
{
	for (int i = 0; i < 89; i++)
		for (int g = 0; g < 89; g++)
			p[i][g] = INT32_MAX;
	for (int i = 0; i < 89; i++)
	{
		for (int g = 0; g < 89; g++)
		{
			if (f[i][g] > 0)
			{
				if (f[i][g] == c[i][g])
					p[i][g] = -sourceP[i][g];
				else
				{
					p[i][g] = -sourceP[i][g];
					p[g][i] = sourceP[i][g];
				}
			}
			else
			{
				if(c[i][g])
					p[g][i] = sourceP[i][g];
			}
		}
	}
}

void fillD()
{
	for (int i = 0; i < 89; i++)
		D[i] = INT32_MAX / 2;
	D[0] = 0;
	for (int i = 0; i < 89; i++)
		for (int first = 0; first < 89; first++)
			for (int second = 0; second < 89; second++)
				if (p[first][second] != INT32_MAX)
					if (D[second] > D[first] + p[first][second])
					{
						D[second] = D[first] + p[first][second];
						from[second] = first;
					}
}

int isAnyContures()
{
	fillD();
	for (int first = 0; first < 89; first++)
		for (int second = 0; second < 89; second++)
			if (p[first][second] != INT32_MAX)
				if (D[second] > D[first] + p[first][second])
					return first;
	return -1;
}

int findEnter(int begin)
{
	int curr = begin;
	bool visited[89];
	for (int i = 0; i < 89; i++)
		visited[i] = false;
	while (!visited[curr])
	{
		visited[curr] = true;
		curr = from[curr];
	}
	return curr;
}

int main()
{
	ofstream out("output.txt");
	pair <int, int> count;
	int flow, curr, begin, total = 0, d = INT32_MAX;
	long double cost = 0;
	count = dataRead();
	if (count.first < count.second)
	{
		swap(first_team, second_team);
		count = make_pair(count.second, count.first);
	}
	fill(count.first - count.second);
	fillSource();
	while (bfs())
	{
		flow = marks[88].flow;
		total += flow;
		curr = 88;
		while (curr != -1)
		{
			marks;
			f[marks[curr].from][curr] += flow;
			f[curr][marks[curr].from] -= flow;
			curr = marks[curr].from;
		}
	}
	fillP();
	while ((begin = isAnyContures()) != -1)
	{
		d = INT32_MAX;
		begin = findEnter(begin);
		curr = begin;
		do
		{
			if (p[from[curr]][curr] < 0)
			{
				if (f[from[curr]][curr] < d)
					d = f[from[curr]][curr];
			}
			else
			{
				if (c[curr][from[curr]] - f[curr][from[curr]] < d)
					d = c[curr][from[curr]] - f[curr][from[curr]];
			}
			curr = from[curr];
		} while (curr != begin);
		curr = begin;
		do
		{
			if (p[from[curr]][curr] < 0)
				f[from[curr]][curr] -= d;
			else
				f[curr][from[curr]] += d;
			curr = from[curr];
		} while (curr != begin);
		fillP();
	}
	for (int i = 0; i < 89; i++)
		for (int g = 0; g < 89; g++)
			if (f[i][g] > 0)
				cost += sourceP[i][g] * f[i][g];
	long long int fullPart = int(cost);
	out << fullPart;
	if (cost - fullPart != 0)
		out << ".5";
	else
		out << ".0";
	return 0;
}