// 
// Solution to problem Easter Eggs
// By Mees de Vries
//
// Expected judgment: ACCEPTED
//
// Binary search + matching, uses Koenig's theorem for finding maximal
// independent set by finding a maximal matching in a biparite graph.


#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <cmath>

using namespace std;

vector<int> vis;
vector<int> match;
double mid;
int N, B, R;
vector<double> x, y;


int aug(int l) {
    if(vis[l]) return 0;
    vis[l] = 1;
    for(int r = B; r < B + R; r++) {
        if(sqrt((x[l]-x[r])*(x[l] - x[r]) + (y[l] - y[r])*(y[l]-y[r])) < mid) {
            if(match[r] == -1 || aug(match[r])) {
                match[r] = l;
                return 1;
            }
        }
    }
    return 0;
}

int main() {
    cin >> N >> B >> R; 
    x = vector<double>(B + R), y = vector<double>(B + R);
    double lo = 0, hi = 0;
    for(int i = 0; i < B + R; i++) {
        cin >> x[i] >> y[i];
        hi = max(hi, 2*sqrt(x[i]*x[i] + y[i]*y[i]));
    }

    while(hi - lo > .00000001) {
        mid = (hi + lo)/2;
        int MCBM = 0;
        match = vector<int>(B + R,-1);
        for(int l = 0; l < B; l++) {
            vis = vector<int>(B + R,0);
            MCBM += aug(l);
        }
        if(MCBM + N <= B + R) {
            lo = mid;
        }
        else {
            hi = mid;
        }
    }
    printf("%.8lf\n",hi);
    return 0;
}