Arcpsod

// implementare: Cristi Dospra
// punctaj: 100p
// complexitate: O(NlogN)

#include <fstream>
#include <algorithm>
#include <cmath>
#include <iomanip>
using namespace std;

#define NMAX 100002

ifstream fin("archpsod.in");
ofstream fout("archpsod.out");

struct point {
    int x, y;
};

point v[NMAX];

inline int sqr(int x) {
    return x * x;
}

inline double dist(point A, point B) {

    return sqrt(1.0 * (sqr(A.x - B.x) + sqr(A.y - B.y)));
}

point Hull[NMAX];

inline int det(point A, point B, point C) {

    return A.x * (B.y - C.y) + B.x * (C.y - A.y) + C.x * (A.y - B.y);
}

int MakeHull(int N) {

    int L = 0;

    for (int i = 1; i <= N; ++i) {
        while (L > 1 && det(Hull[L-1], Hull[L], v[i]) <= 0)
            L--;
        Hull[++L] = v[i];
    }

    int l = L;

    for (int i = N; i >= 1; --i) {
        while (L > l && det(Hull[L-1], Hull[L], v[i]) <= 0)
            L--;
        Hull[++L] = v[i];
    }

    L--;

    return L;
}

inline bool cmp(point A, point B) {

    if (A.x == B.x)
        return A.y < B.y;

    return A.x < B.x;
}

int main() {

    int N;
    fin >> N;

    for (int i = 1; i <= N; ++i)
        fin >> v[i].x >> v[i].y;

    sort(v + 1, v + N + 1, cmp);

    int T = MakeHull(N);

    double Sol = 0.0;

    for (int i = 1; i <= T; ++i)
        for (int j = i + 1; j <= T; ++j)
            Sol = max(Sol, dist(Hull[i], Hull[j]));

    fout << fixed << setprecision(6) << Sol << "\n";

    return 0;
}