/* 
 * Author: $%U%$
 * Time: $%Y%$-$%M%$-$%D%$ $%h%$:$%m%$:$%s%$
 */
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,a,b) for(ll i=(a);i<=(b);i++)
#define per(i,a,b) for(ll i=(a);i>=(b);i--)
#define re(i,a,b) for(ll i=(a);i<(b);i++)
#define pe(i,a,b) for(ll i=(a);i>(b);i--)
#define getchar()(p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
char buf[1<<21],*p1=buf,*p2=buf;
template <typename T>
inline void read(T& r) {
	r=0;bool w=0; char ch=getchar();
	while(ch<'0'||ch>'9') w=ch=='-'?1:0,ch=getchar();
	while(ch>='0'&&ch<='9') r=r*10+(ch^48), ch=getchar();
	r=w?-r:r;
}
template <typename T>
inline void readupp(T& r){
	r=0;
	char ch=getchar();
	while(ch>'Z'||ch<'A')ch=getchar();
	r=ch;
}
template <typename T>
inline void readlow(T& r){
	r=0;
	char ch=getchar();
	while(ch>'z'||ch<'a')ch=getchar();
	r=ch;
}
template <typename T>
inline void readdig(T& r){
	r=0;
	char ch=getchar();
	while(ch>'9'||ch<'0')ch=getchar();
	r=ch-'0';
}
template <typename T>
inline void readvisi(T& r){
	r=0;
	char ch=getchar();
	while(ch>126||ch<33)ch=getchar();
	r=ch;
}
template <typename T>
inline ll readlowstr(T& r){
	ll n=0;
	char ch=getchar();
	while(ch>'z'||ch<'a')ch=getchar();
	while(ch<='z'&&ch>='a')r[++n]=ch-'a',ch=getchar();
	return n;
}
template <typename T>
inline ll readuppstr(T& r){
	ll n=0;
	char ch=getchar();
	while(ch>'Z'||ch<'A')ch=getchar();
	while(ch<='Z'&&ch>='A')r[++n]=ch-'A',ch=getchar();
	return n;
}
template <typename T>
inline ll readdigstr(T& r){
	ll n=0;
	char ch=getchar();
	while(ch>'9'||ch<'0')ch=getchar();
	while(ch<='9'&&ch>='0')r[++n]=ch-'0',ch=getchar();
	return n;
}
template <typename T>
inline ll readvisistr(T& r){
	ll n=0;
	char ch=getchar();
	while(ch>126||ch<33)ch=getchar();
	while(ch<=126&&ch>=33)r[++n]=ch,ch=getchar();
	return n;
}
const ll MOD=998244353;
ll gcd(ll A,ll B){return B?gcd(B,A%B):A;}
template<typename T>
void chkmax(T&A,T B){if(A<B)A=B;}
template<typename T>
void chkmin(T&A,T B){if(A>B)A=B;}
template<typename T>
T Madd(T A,T B){return A+B>=MOD?A+B-MOD:A+B;}
template<typename T>
T Msub(T A,T B){return A-B<0?A-B+MOD:A-B;}
template<typename T>
void MODed(T &A){A%=MOD;A+=(A<0?MOD:0);}
ll pw(ll A,ll B){
	ll res=1;
	while(B){
		if(B&1)res=res*A%MOD;
		A=A*A%MOD;
		B>>=1;
	}
	return res;
}
void _FILE(string s){
	freopen((s+".in").c_str(),"r",stdin);
	freopen((s+".out").c_str(),"w",stdout);
}
const ll N=200003,M=3003,INF=2000000000000000007ll;
ll n;
const double eps=1e-9;
struct vect{
	double x,y;
	vect(){x=0,y=0;}
	template<typename TT>
	vect(TT a,TT b){x=a,y=b;}
	vect operator +(const vect &B){return vect(x+B.x,y+B.y);}
	vect operator -(const vect &B){return vect(x-B.x,y-B.y);}
	double operator *(const vect&B){return x*B.x+y*B.y;}
	double operator ^(const vect&B){return x*B.y-y*B.x;}
	double len(){return sqrt(x*x+y*y);}
};
struct line{
	vect p,v;
	line(){}
	line(vect A,vect B){p=A,v=B;}
};
double dist(line A,vect B){
	return fabs((B-A.p)^A.v)/A.v.len();
}
vect a[N],b[N];
bool vst[N];
int main(){
	read(n);
	rep(i,0,n-1)read(a[i].x),read(a[i].y);
	rep(i,0,n-1){
		if(fabs((a[i]-a[(i+n-1)%n])^(a[(i+1)%n]-a[i]))<eps)vst[i]=1;
	}
	ll cnt=0;
	rep(i,0,n-1)if(!vst[i])b[cnt++]=a[i];
	n=cnt;
	ll pos1=1,pos2=1;
	double ans=0;
	rep(i,0,n-1){
		line tmp(b[i],b[(i+1)%n]-b[i]);
		while(dist(tmp,b[pos1])<dist(tmp,b[(pos1+1)%n])-eps)pos1++;
		pos2=pos1;
		while(dist(tmp,b[pos2])<dist(tmp,b[(pos2+1)%n])+eps)pos2++;
		ans=max(ans,(b[pos1]-b[i]).len());
		ans=max(ans,(b[pos1]-b[(i+1)%n]).len());
		ans=max(ans,(b[pos2]-b[i]).len());
		ans=max(ans,(b[pos2]-b[(i+1)%n]).len());
	}
	cout<<fixed<<setprecision(9)<<ans;
	return 0;
}