#include<bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
template<typename F, typename S>
ostream &operator<<(ostream &os, const pair<F, S> &p) {
    return os << "(" << p.first << ", " << p.second << ")";
}
template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    os << "{";
    typename vector<T>::const_iterator it;
    for (it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) os << ", ";
        os << *it;
    }
    return os << "}";
}
template<typename T>
ostream &operator<<(ostream &os, const set<T> &v) {
    os << "[";
    typename set<T>::const_iterator it;
    for (it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) os << ", ";
        os << *it;
    }
    return os << "]";
}
template<typename F, typename S>
ostream &operator<<(ostream &os, const map<F, S> &v) {
    os << "[";
    typename map<F, S>::const_iterator it;
    for (it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) os << ", ";
        os << it->first << " = " << it->second;
    }
    return os << "]";
}
#define debug(x) cerr << #x << " = " << x << endl;
#define trace1(x)                cerr<<#x<<": "<<x<<endl
#define trace2(x, y)             cerr<<#x<<": "<<x<<" | "<<#y<<": "<<y<<endl
#define trace3(x, y, z)          cerr<<#x<<":" <<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<endl
#define trace4(a, b, c, d)       cerr<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<endl
#define trace5(a, b, c, d, e)    cerr<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<" | "<<#e<< ": "<<e<<endl
#define trace6(a, b, c, d, e, f) cerr<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<" | "<<#e<< ": "<<e<<" | "<<#f<<": "<<f<<endl


typedef long long int ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long int> vll;
typedef pair<int, int> pii;
typedef pair<long long int, long long int> pll;
typedef map<int, int> mii;
typedef vector< pair<int, int> > vpii;

#define endl "\n";
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(),(c).end()
#define tr(cont, it) for(decltype((cont).begin()) it = (cont).begin(); it != (cont).end(); it++)
#define present(c, x) ((c).find(x) != (c).end())
#define cpresent(c, x) (find(all(c),x) != (c).end())
#define F first
#define S second


const ld PI=acos(-1.0);
const ll mod = 1000000007;
const ll inf = (ll) 1e15;

ll power(ll a, ll b, ll m = mod) {if (b == 0) return 1; if (b == 1) return (a % m); ll x = power(a, b / 2, m); x = (x * x) % m; if (b % 2) x = (x * a) % m;return x;}
ll min(ll a, ll b) { return (a < b ? a : b); }

const int N=1e2+5;
const int M=1e5+5;

pair<ll,ll> a[2*N],sum[N];
int n;

int quadrant(pair<int,int> p)
{
    int x=p.first,y=p.second;
    if(x>=0 && y>=0)
        return 1;
    else if(x<0 && y>=0)
        return 2;
    else if(x<0 && y<0)
        return 3;
    else return 4;
}

ll cross(pair<int,int> p1,pair<int,int>  p2)
{
    ll ret=(ll)p1.first*p2.second-(ll)p1.second*p2.first;
    return ret;
}

bool cmp(pair<int,int> p1,pair<int,int> p2)
{
   int q1=quadrant(p1);
   int q2=quadrant(p2);
   if(q1!=q2)
       return q1<q2;
   return cross(p1,p2)>0;
}

void solve() {

    cin >> n;
    for(int i=1;i<=n;i++)
    {
        cin >> a[i].first >> a[i].second ;
    }
    sort(a+1,a+n+1,cmp);
    for(int i=1;i<=n;i++)
    {
        a[n+i]=a[i];
    }
    for(int i=1;i<=2*n;i++)
    {
        sum[i]={sum[i-1].first+a[i].first,sum[i-1].second+a[i].second};
    }
    ld ans=0;
    for(int i=1;i<=n;i++)
    {
        for(int j=i;j<n+i;j++)
        {
            ll tx=sum[j].first-sum[i-1].first;
            ll ty=sum[j].second-sum[i-1].second;
            ld tans=tx*tx + ty* ty;
            ans=max(ans,sqrt(tans));
        }
    }
    printf("%0.20lf\n", (double)ans );
}

int main() {
    IOS;
    int t = 1, num = 1;   ///// change this t for number of testcase globally
    while (t--) {
        solve();
    }
    return 0;
}

/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?), set tle
    * do smth instead of nothing and stay organized
*/

Measured memory_bytes: 256