#include <bits/stdc++.h>
#define ffor(i,a,b) for(int i=(a);i<=(b);i++)
#define roff(i,a,b) for(int i=(a);i>=(b);i--)
using namespace std;
const int MAXN=100000+10;
int n;
struct VEC {double x,y;}v[MAXN<<1],s;
double ans;
int getsq(VEC v) {
	if(v.x>=0&&v.y>=0) return 1;
	if(v.x<0&&v.y>=0) return 2;
	if(v.x<0&&v.y<0) return 3;
	return 4;	
}
bool operator <(VEC a,VEC b) {
	if(getsq(a)!=getsq(b)) return getsq(a)<getsq(b);
	return a.x*b.y-a.y*b.x>0;
}
VEC operator +(VEC A,VEC B) {return {A.x+B.x,A.y+B.y};}
VEC operator -(VEC A,VEC B) {return {A.x-B.x,A.y-B.y};}
int main() {
	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	cin>>n;
	ffor(i,1,n) cin>>v[i].x>>v[i].y;
	VEC vc={0,0};
	ffor(i,1,n) vc=vc+v[i];
	sort(v+1,v+n+1);
	ffor(i,1,n) v[i+n]=v[i];
	int l=1,r=1; s=v[1],ans=max(ans,s.x*s.x+s.y*s.y);
	while(v[l].x*v[r+1].y-v[l].y*v[r+1].x>0) {
		r++,s=s+v[r],ans=max(ans,s.x*s.x+s.y*s.y);
	}	
	ffor(i,2,n) {
		l++,s=s-v[l-1];
		if(r<l) s=v[l],r=l;
		ans=max(ans,s.x*s.x+s.y*s.y);
		while(v[l].x*v[r+1].y-v[l].y*v[r+1].x>0) {
			r++,s=s+v[r],ans=max(ans,s.x*s.x+s.y*s.y);
		}
	}
	cout<<fixed<<setprecision(3)<<ans;
	return 0;
}

#include<bits/stdc++.h>
#define ffor(i,a,b) for(int i=(a);i<=(b);i++)
#define roff(i,a,b) for(int i=(a);i>=(b);i--)
using namespace std;
const int MAXN=100000+10;
int n;
struct VEC {double x,y;}v[MAXN<<1],s;
double ans;
int getsq(VEC v) {
	if(v.x>=0&&v.y>=0) return 1;
	if(v.x<0&&v.y>=0) return 2;
	if(v.x<0&&v.y<0) return 3;
	return 4;	
}
bool operator <(VEC a,VEC b) {
	if(getsq(a)!=getsq(b)) return getsq(a)<getsq(b);
	return a.x*b.y-a.y*b.x>0;
}
VEC operator +(VEC A,VEC B) {return {A.x+B.x,A.y+B.y};}
VEC operator -(VEC A,VEC B) {return {A.x-B.x,A.y-B.y};}
int main() {
	ios::sync_with_stdio(False),cin.tie(0),cout.tie(0);
	cin>>n;
	ffor(i,1,n) cin>>v[i].x>>v[i].y;
	VEC vc={0,0};
	ffor(i,1,n) vc=vc+v[i];
	sort(v+1,v+n+1);
	ffor(i,1,n) v[i+n]=v[i];
	int l=1,r=1; s=v[1],ans=max(ans,s.x*s.x+s.y*s.y);
	while(v[l].x*v[r+1].y-v[l].y*v[r+1].x>0) {
		r++,s=s+v[r],ans=max(ans,s.x*s.x+s.y*s.y);
	}	
	ffor(i,2,n) {
		l++,s=s-v[l-1];
		if(r<l) s=v[l],r=l;
		ans=max(ans,s.x*s.x+s.y*s.y);
		while(v[l].x*v[r+1].y-v[l].y*v[r+1].x>0) {
			r++,s=s+v[r],ans=max(ans,s.x*s.x+s.y*s.y);
		}
	}
	cout<<fixed<<setprecision(3)<<ans;
	return 0;
}