#include<bits/stdc++.h>
#define db long double
#define rep(i,j,k) for(int i=j;i<=k;i++)
using namespace std;
const int N=5e5+5;
const db eps=1e-10;
int n;
db ans;
struct ss{db x,y;}d[N];
ss js(ss a,ss b){return {a.x-b.x,a.y-b.y};}
db dis(ss a){return sqrt(a.x*a.x+a.y*a.y);}
db cr(ss a,ss b){return a.x*b.y-a.y*b.x;}
signed main(){
    scanf("%d",&n);
    rep(i,1,n) scanf("%Lf%Lf",&d[i].x,&d[i].y);
    int zz=3;
    rep(i,1,n){
        int d1=i,d2=i%n+1;
        while(zz%n+1!=i&&cr(js(d[zz%n+1],d[d1]),js(d[d2],d[d1]))<cr(js(d[zz],d[d1]),js(d[d2],d[d1]))+eps) ans=max({ans,dis(js(d[zz],d[d1])),dis(js(d[zz],d[d2]))}),zz=zz%n+1;
        ans=max({ans,dis(js(d[zz],d[d1])),dis(js(d[zz],d[d2]))});
    }printf("%.10Lf",ans);
}