#include<bits/stdc++.h>
using namespace std;

#define double long double
const int maxn = 20;
const double inf = 1e18;

double dis(int sx, int sy, int ex, int ey){
	return sqrt((sx - ex) * (sx - ex) + (sy - ey) * (sy - ey));
}

int n, m;
double x[maxn], y[maxn];
double speed, ans = inf;
double f[maxn][1<<maxn]; //当前在第i个，城市状态为mask，速度为2^__builtin_popcount(mask>>n) 

int main(){
	ios::sync_with_stdio(0);
	cin >> n >> m;
	for(int i = 0; i < n + m; i++) cin >> x[i] >> y[i];
	for(int i = 0; i < n + m; i++)
		for(int mask = 0; mask < 1 << (n + m); mask++) f[i][mask] = inf;
	for(int i = 0; i < n + m; i++) f[i][1<<i] = dis(0, 0, x[i], y[i]);
	
	for(int mask = 1; mask < 1 << (n + m); mask++){
		speed = pow(2, __builtin_popcount(mask >> n)); 
//		cout << speed << endl;
		for(int i = 0; i < n + m; i++) if((mask >> i) & 1)
			for(int j = 0; j < n + m; j++) if(!((mask >> j) & 1)) 
				f[j][mask^(1<<j)] = min(f[j][mask^(1<<j)], f[i][mask] + dis(x[i], y[i], x[j], y[j]) / speed);
	}
	
	for(int i = 0; i < n + m; i++)
		for(int mask = (1 << n) - 1; mask < 1 << (n + m); mask += 1 << n){
			speed = pow(2, __builtin_popcount(mask >> n));
			ans = min(ans, f[i][mask] + dis(0, 0, x[i], y[i]) / speed);
		}
		
	cout << fixed << setprecision(10) << ans << endl;
	return 0;
}