#define _CRT_SECURE_NO_WARNINGS
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <set>
#include <map>
#include <deque>
#include <cmath>
#include <queue>
#include <random>
#include <bitset>
#include <time.h>
#include <string>
#include <chrono>
#include <cstdio>
#include <vector>
#include <cstdlib>
#include <iomanip>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>
//++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++
#define itn int
#define endl '\n'
#define mp make_pair
#define pbc push_back
#define pob pop_back()
#define empb emplace_back
#define sp system("pause")
#define queuel queue<long long>
#define matrix vector<vector<ll>>
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define pin(p) cin >> p.first >> p.second;
#define rev(v) reverse(v.begin(),v.end());
#define mx(v) max_element(v.begin(), v.end());
#define mn(v) min_element(v.begin(), v.end());
#define dig(c) (c >=' 0' && c <= '9') ? 1 : 0
#define sout(s, c) for(auto i : s) cout << i << c;
#define pout(p) cout << p.first << " " << p.second;
#define er(v, l, r) erase(v.begin() + l, v.begin() + r);
#define vin(v) for(ll i = 0; i < v.size(); i++) cin >> v[i];
#define vout(v, c) for(int i = 0; i < v.size(); i++) cout << v[i] << c;
#define pushi(v, a) for(int i = 0; i < a.size(); i++) v.push_back(a[i]);
#define sin(s, n) for(int i = 0; i < n; i++){int a; cin >> a; s.insert(a);}
#define fastio() ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0);
//++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++
using namespace std;
/*▄███████▀▀▀▀▀▀███████▄
░▐████▀▒ЗАПУСКАЕМ▒▀██████▄
░███▀▒▒▒▒▒ДЯДЮ▒▒▒▒▒▒▀█████
░▐██▒▒▒▒▒▒БОГДАНА▒▒▒▒▒████▌
░▐█▌▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒████▌
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░▀▄▐▒▀▀▀▀▒▒▒▒▒▒▀▀▀▒▒▒▒▒▒█
░░░▀▌▒▄██▄▄▄▄████▄▒▒▒▒█▀
░░░░▄██████████████▒▒▐▌
░░░▀███▀▀████▀█████▀▒▌
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░░░░░▌▒▒▒▒▀▀▀▒▒▒▒▒▒▒▐*/
//++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
//++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++
const ll INF = 1000LL * 1000 * 1000 * 1000 * 1000 * 1000;
const int inf = 1000000000 + 228;
const ld PI = acos(-1.0);
const ll mod1 = inf * inf + 1337 * 42 + 57 * 179 + 228;
const ll mod2 = inf + 9;
const ll bigmod = 1LL * inf * 100 + 3;
const int MAXN = 10005;
const ld EPS = 1e-10;
const int N = 300228;
ll hp = 1e6 + 3;
struct point
{
	ld x, y;

};

struct line
{
	ld a,b,c;
};
line getln(point a, point b)
{
	line m;
	m.a = b.y - a.y;
	m.b = a.x - b.x;
	m.c = -(m.a * a.x + m.b  * a.y);
	return m;
}
ld det(ld a, ld b, ld c, ld d)
{
	return a * d - b * c;
}
point  intersect(line m, line n)
{

	ld zn = det(m.a, m.b, n.a, n.b);
	if (abs(zn) < EPS)
	{
		return { inf, inf };
	}
	point res;
	res.x = -det(m.c, m.b, n.c, n.b) / zn;
	res.y = -det(m.a, m.c, n.a, n.c) / zn;
	return res;
}
ld hypot(point a, point b)
{
	return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}
bool belong(point a, point b, point c)
{
	return abs(hypot(a, b) - hypot(a, c) - hypot(b, c)) < EPS;
}
bool operator==(point a, point b)
{
	return abs(a.x - b.x) < EPS && abs(a.y - b.y) < EPS;
}
bool kekkek(line a, line b)
{
	return abs(det(a.a, a.b, b.a, b.b)) < EPS && abs(det(a.b, a.c, b.b, b.c)) < EPS  && abs(det(a.a, a.c, b.a, b.c)) < EPS;
}
point operator+(point a, point b)
{
	return { a.x + b.x, a.y + b.y };
}
point vec(point a, point b)
{
	return { b.x - a.x, b.y - a.y };
}
point operator/(point a, ld x)
{
	return { a.x / x, a.y / x };
}
ld operator*(point a, point b)
{
	return a.x * b.y - a.y* b.x;
}
ld operator%(point a, point b)
{
	return a.x * b.x + a.y * b.y;
}
bool help(point a, vector<point > b)
{
	ld sum = 0;
	for (int i = 0; i < b.size(); ++i)
	{
		point x = b[i];
		point y = b[(i + 1) % b.size()];
		if (a == x || belong(x, y, a))
		{
			return 1;
		}
		sum += atan2(vec(a, x) * vec(a, y), vec(a, x) % vec(a, y));
	}
	return abs(abs(sum) - 2 * PI) < EPS ;
}
bool check(point a, point b, vector<point> kek)
{
	point mid = (a + b) / 2;
	if (help(mid, kek)) return 0;
	line fs = getln(a, b);
	for (int i = 0; i < kek.size(); ++i)
	{
		point ka = kek[i];
		point now = kek[(i + 1) % kek.size()];
		line ss = getln(ka, now);
		point x = intersect(ss, fs);
		if (kekkek(fs, ss) && (belong(a,b,ka) && belong(a,b,now))) return 0;
		if (x == ka || x == now)
		{
			continue;
		}
		if (belong(ka, now, x) && belong(a,b,x))
		{
			return 0;
		}
	}
	return 1;
}
signed main()
{
	fastio();
	int  n;
	cin >> n;
	vector<point> a(n);
	for (int i = 0; i < n; ++i)
	{
		cin >> a[i].x >> a[i].y;
	}
	int m;
	cin >> m;
	vector<point> x(m);
	for (int i = 0; i < m; ++i)
	{
		cin >> x[i].x >> x[i].y;
	}
	vector<vector<ld>> d(n + m, vector<ld>(n + m, inf));
	for (int i = 0; i < n + m; ++i) d[i][i] = 0;
	for (int i = m; i < n + m - 1; ++i)
	{
		d[i][i + 1] = d[i + 1][i] = hypot(a[i - m], a[i - m + 1]);
	}
	d[n + m - 1][m] = d[m][n + m - 1] = hypot(a[n - 1], a[0]);
	for (int i = 0; i < m; ++i)
	{
		for (int j = m; j < n + m; ++j)
		{
			if (check(x[i], a[j - m], a))
			{
				d[i][j] = d[j][i] = hypot(x[i], a[j - m]);
			}
		}
	}
	for (int i = m; i < n + m; ++i)
	{
		for (int j = m; j < n + m; ++j)
		{
			if (i == m && j == m + 2 )
			{
				cout << "";
			}
			if (i == m + 2 && j == m)
			{
				cout << "";
			}
			if (check(a[i - m], a[j - m], a))
			{
				d[i][j] = d[j][i] = hypot(a[i - m], a[j - m]);
			}
		}
	}
	for (int i = 0; i < m; ++i)
	{
		for (int j = 0; j < m; ++j)
		{
			if (check(x[i], x[j], a))
			{
				d[i][j] = d[j][i] = hypot(x[i], x[j]);
			}
		}
	}
	/*
	for (int i = 0; i < n + m; ++i)
	{
		for (int j = 0; j < n + m; ++j)
		{
			cout << d[i][j] << ' ';
		}

		cout << endl;

	}
	sp;*/
	for (int k = 0; k < n + m;++k)
	{
		for (int i = 0; i < n + m; ++i)
		{
			for (int j = 0; j < n + m; ++j)
			{
				if (i == 0 && j == 5)
				{
					cout << "";
				}
				if (d[i][k] + d[k][j] - EPS < d[i][j])
				{
					d[i][j] = d[i][k] + d[k][j];
				}
			}
		}
	}
	ld ans = 0;
	//cout << endl;
	/*for (int i = 0; i < n + m; ++i)
	{
		for (int j = 0; j < n + m; ++j)
		{
			cout << d[i][j] << ' ';
		}

		cout << endl;

	}
	sp;
	for (int i = 0; i < m; ++i)
	{
		for (int j = 0; j < m; ++j)
		{
			cout << d[i][j] << ' ';
		}
		cout << endl;
	}
	sp;*/
for (int i = 0; i < m; ++i)
	{
		for (int j = 0; j < m; ++j)
		{
			if (d[i][j]  + EPS > ans)
			{
				ans = d[i][j];
			}
		}
	}
	cout << fixed << setprecision(20) << ans;
	//sp;
}