Problem: Find the diameter of a convex polygon g. In other words, find a pair of points that have maximum distance between them.

Constraints

* 3 ≤ n ≤ 80000
* -100 ≤ xi, yi ≤ 100
* No point in the g will occur more than once.

Input


n
x1 y1
x2 y2
:
xn yn


The first integer n is the number of points in g.

In the following lines, the coordinate of the i-th point pi is given by two real numbers xi and yi. The coordinates of points are given in the order of counter-clockwise visit of them. Each value is a real number with at most 6 digits after the decimal point.

Output

Print the diameter of g in a line. The output values should be in a decimal fraction with an error less than 0.000001.

Examples

Input

3
0.0 0.0
4.0 0.0
2.0 2.0


Output

4.00


Input

4
0.0 0.0
1.0 0.0
1.0 1.0
0.0 1.0


Output

1.414213562373

Solution (in CPP):

Solution:
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <algorithm>
#include <sstream>
#include <cmath>
#include <set>
#include <iomanip>
#include <deque>
#include <stdio.h>
using namespace std;

#define REP(i,n) for(int (i)=0;(i)<(int)(n);(i)++)
#define RREP(i,n) for(int (i)=(int)(n)-1;i>=0;i--)
#define FOREACH(i,Itr) for(auto (i)=(Itr).begin();(i)!=(Itr).end();(i)++)
#define REMOVE(Itr,n) (Itr).erase(remove((Itr).begin(),(Itr).end(),n),(Itr).end())
#define PB_VEC(Itr1,Itr2) (Itr1).insert((Itr1).end(),(Itr2).begin(),(Itr2).end())
#define UNIQUE(Itr) sort((Itr).begin(),(Itr).end()); (Itr).erase(unique((Itr).begin(),(Itr).end()),(Itr).end())
#define LBOUND(Itr,val) lower_bound((Itr).begin(),(Itr).end(),(val))
#define UBOUND(Itr,val) upper_bound((Itr).begin(),(Itr).end(),(val))
#define EPS 1.0e-8
#define MOD 1000000007
typedef long long ll;

struct Point {
    double x,y;
    Point(){}
    Point(double _x, double _y):x(_x),y(_y){}
    bool operator < (const Point &a) const {
        return (x==a.x) ? (y<a.y) : (x<a.x);
    }
};
Point operator +(const Point &a,const Point &b){return Point(a.x+b.x,a.y+b.y);}
Point operator -(const Point &a,const Point &b){return Point(a.x-b.x,a.y-b.y);}
Point operator *(const Point &a,double k){return Point(a.x*k,a.y*k);}

struct Segment {
    Point p1,p2;
    Segment(){}
    Segment(Point _p1, Point _p2):p1(_p1),p2(_p2){}
    Segment(double x1, double y1, double x2, double y2)
    :p1(Point(x1,y1)),p2(Point(x2,y2)){}
};

struct Circle {
    Point c; double r;
    Circle(){}
    Circle(Point _c, double _r):c(_c),r(_r){}
    Circle(double x, double y, double _r):c(Point(x,y)),r(_r){}
};

typedef Point Vector;
typedef Segment Line;
typedef vector<Point> Polygon;

double dot(Vector a, Vector b){return a.x*b.x + a.y*b.y;}
double cross(Vector a, Vector b){return a.x*b.y - a.y*b.x;}
double norm(Vector a){return sqrt(dot(a,a)*dot(a,a));}

Point Project(Segment s, Point p) {
    Vector base = s.p2 - s.p1;
    double r = dot(p - s.p1, base) / norm(base);
    return s.p1 + base * r;
}

Point Reflect(Segment s, Point p) {
    return p + (Project(s,p) - p) * 2.0;
}

double DistanceLinePoint(Line s, Point p) {
    Vector dist = Project(s,p) - p;
    return sqrt(norm(dist));
}

double DistanceSegmentPoint(Segment s, Point p) {
    if(dot(s.p2 - s.p1, p -s.p1)<0.0)return sqrt(norm(p - s.p1));
    if(dot(s.p1 - s.p2, p -s.p2)<0.0)return sqrt(norm(p - s.p2));
    return DistanceLinePoint(s,p);
}

const int COUNTER_CLOCKWISE = 1;
const int CLOCKWISE = -1;
const int ONLINE_BACK = 2;
const int ONLINE_FRONT = -2;
const int ON_SEGMENT = 0;
int CounterClockwise(Point p0, Point p1, Point p2) {
    Vector a = p1 - p0;
    Vector b = p2 - p0;
    if(cross(a,b)>1.0e-8)return COUNTER_CLOCKWISE;
    if(cross(a,b)<-1.0e-8)return CLOCKWISE;
    if(dot(a,b)<-1.0e-8)return ONLINE_BACK;
    if(norm(a)<norm(b))return ONLINE_FRONT;
    return ON_SEGMENT;
}

bool Intersect(Point p1, Point p2, Point p3, Point p4) {
   return (CounterClockwise(p1,p2,p3) * CounterClockwise(p1,p2,p4) <= 0 &&
           CounterClockwise(p3,p4,p1) * CounterClockwise(p3,p4,p2) <= 0);
}

bool Intersect(Segment s1, Segment s2) {
    return Intersect(s1.p1,s1.p2,s2.p1,s2.p2);
}

Point CrossPoint(Segment s1, Segment s2){
    Vector base = s2.p2 - s2.p1;
    double d1 = abs(cross(base,s1.p1 - s2.p1));
    double d2 = abs(cross(base,s1.p2 - s2.p1));
    double t = d1 / (d1+d2);
    return s1.p1 + (s1.p2-s1.p1) * t;
}

Polygon ConvexHull(vector<Point> pos) {
    int n = (int)pos.size(), k = 0;
    sort(pos.begin(),pos.end());
    Polygon ch(2*n);
    for(int i=0;i<n;ch[k++]=pos[i++])
        while(k>=2 && CounterClockwise(ch[k-2],ch[k-1],pos[i])<=0)--k;
    for(int i=n-2,t=k+1;i>=0;ch[k++]=pos[i--])
        while(k>=t && CounterClockwise(ch[k-2],ch[k-1],pos[i])<=0)--k;
    ch.resize(k-1);
    return ch;
}

double ConvexDiameter(Polygon &pos) {
    int n = (int)pos.size();
    int is = 0, js = 0;
    for(int i=1;i<n;++i) {
        if (pos[i].y > pos[is].y) is = i;
        if (pos[i].y < pos[js].y) js = i;
    }
    double maxd = norm(pos[is]-pos[js]);
    
    int i, maxi, j, maxj;
    i = maxi = is;
    j = maxj = js;
    do{
        if(cross(pos[(i+1)%n]-pos[i],pos[(j+1)%n]-pos[j])>=0)j=(j+1)%n;
        else i=(i+1)%n;
        if(norm(pos[i]-pos[j]) > maxd) {
            maxd = norm(pos[i]-pos[j]);
            maxi = i; maxj = j;
        }
    }while(i!=is || j!=js);
    return sqrt(maxd);
}

int main(){
    
    int n; cin>>n;
    vector<Point> pos(n);
    REP(i,n)cin>>pos[i].x>>pos[i].y;
    
    Polygon p = ConvexHull(pos);
    cout<<fixed<<setprecision(10)<<ConvexDiameter(p)<<endl;
    
    return 0;
}