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

using namespace std;

class Pos {
public:
    int x;
    int y;
    Pos() {

    }
    Pos(int x, int y) {
        this->x = x;
        this->y = y;
    }
    int distance(Pos pos) {
        return (x - pos.x) * (x - pos.x) + (y - pos.y) * (y - pos.y);
    }
};


bool check[1000];
Pos all_pos[1000];
int N;

void foo(int index, vector<Pos> &poss) {
    for (int i = 0; i < N; i++) {
        if (check[i]) {
            continue;
        }
        int distance = all_pos[index].distance(all_pos[i]);
        if (distance <= 100) {
            check[i] = true;
            poss.push_back(all_pos[i]);
            foo(i, poss);
        }
    }
}

int main() {
    cin >> N;
    for (int i = 0; i < N; i++) {
        check[i] = false;
    }
    if (N == 0) {
        cout << 1 << endl;
        return 0;
    }
    int ans = 0;
    for (int i = 0; i < N; i++) {
        int x, y;
        cin >> x >> y;
        all_pos[i] = Pos(x, y);
    }
    for (int i = 0; i < N; i++) {
        if (check[i]) {
            continue;
        }
        vector<Pos> poss;
        poss.push_back(all_pos[i]);
        foo(i, poss);
        for (int j = 0; j < poss.size(); j++) {
            for (int k = j; k < poss.size(); k++) {
                ans = max(ans, poss[j].distance(poss[k]));
            }
        }
    }
    printf("%10f\n", sqrt(ans) + 2);
    return 0;
}