#define _USE_MATH_DEFINES
#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
#define _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS
#define _CRT_SECURE_NO_WARNINGS
//#include <bits/stdc++.h>

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <bitset>
#include <unordered_map>
#include <unordered_set>
#include <cassert>
#include <fstream>
#include <array>
#include <string>
#include <cstring>
#include <functional>
#include <ctime>
#include <iostream>
#include <unordered_set>

#include <nmmintrin.h>
#include <mmintrin.h>
#include <emmintrin.h>


using namespace std;

#define dprint(Exp,...) if(Exp){fprintf(stderr, __VA_ARGS__);}
#define printe(...) fprintf(stderr, __VA_ARGS__);
//#define printe(...) void();
#define printE(...) fprintf(stderr, __VA_ARGS__);
//#define printE(...) void();


#define PrtExp(_Exp)  cerr<< #_Exp <<" = "<< (_Exp)
#define PrtExpN(_Exp)  cerr<< #_Exp <<" = "<< (_Exp) <<"\n"

#define SINT(n) scanf("%d",&n)
#define SINT2(n,m) scanf("%d %d",&n,&m)
#define SINT3(n,m,o) scanf("%d %d %d",&n,&m,&o)
#define SINT4(n,m,o,P) scanf("%d %d %d %d",&n,&m,&o,&P)
#define SINT5(n,m,o,P,q) scanf("%d %d %d %d %d",&n,&m,&o,&P,&q)
#define SLL(n) scanf("%lld",&n)
#define SLL2(n,m) scanf("%lld %lld",&n,&m)
#define SLL3(n,m,o) scanf("%lld %lld %lld",&n,&m,&o)
#define SST(s) scanf("%s",s)
#define SCH(c) scanf("%c",&c)

#define GC() getchar()

#define PINT(n) printf("%d",(int)(n))
#define PINT2(n,m) printf("%d %d",(int)(n),(int)(m))
#define PINT3(n,m,l) printf("%d %d %d",(int)(n),(int)(m),(int)(l))
#define PLL(n) printf("%lld",(long long)(n))
#define PST(s) printf("%s",(s))
#define PCH(s) printf("%c",(s))

#define PINTN(n) printf("%d\n",(int)(n))
#define PINT2N(n,m) printf("%d %d\n",(int)(n),(int)(m))
#define PINT3N(n,m,l) printf("%d %d %d\n",(int)(n),(int)(m),(int)(l))
#define PLLN(n) printf("%lld\n",(long long)(n))
#define PSTN(s) printf("%s\n",(s))
#define PCHN(s) printf("%c\n",(s))

#define PSP() printf(" ")
#define PN() printf("\n")

#define PC(c) putchar(c)
#define CSP (' ')
#define SN ("\n")

#define rep(i,a) for(int i=0;i<a;i++)
#define reP(i,a) for(int i=0;i<=a;i++)
#define Rep(i,a) for(int i=a-1;i>=0;i--)
#define ReP(i,a) for(int i=a;i>=0;i--)

#define rEp(i,a) for(i=0;i<a;i++)
#define rEP(i,a) for(i=0;i<=a;i++)
#define REp(i,a) for(i=a-1;i>=0;i--)
#define REP(i,a) for(i=a;i>=0;i--)

#define repft(i,a,b) for(int i=a;i<b;i++)
#define repfT(i,a,b) for(int i=a;i<=b;i++)
#define Repft(i,a,b) for(int i=a-1;i>=b;i--)
#define RepfT(i,a,b) for(int i=a;i>=b;i--)

#define foreach(a,it) for(auto it = a.begin(); it != a.end(); ++it)

#define FILL(a,v) fill(begin(a),end(a), v)
#define FILL0(a) memset(a,0,sizeof(a))
#define FILL1(a) memset(a,-1,sizeof(a))

typedef long long ll;

typedef unsigned long long ull;
typedef pair<int, int> Pi;
typedef pair<ll, ll>   Pll;


const int INF = 1'010'000'000; // 0x3C33'6080
const ll INFLL = 0x1f1f1f1f1f1f1f1fLL;//2,242,545,357,980,376,863

template <class A, class B> inline ostream& operator<<(ostream& st, const pair<A, B>& P) { return st << "(" << P.first << "," << P.second << ")"; };
template <class A, class B> inline pair<A, B> operator+(const pair<A, B>& P, const pair<A, B>& Q) { return pair<A, B>(P.first + Q.first, P.second + Q.second); };
template <class A, class B> inline pair<A, B> operator-(const pair<A, B>& P, const pair<A, B>& Q) { return pair<A, B>(P.first - Q.first, P.second - Q.second); };

#define fs  first
#define sc  second

int bitCount(unsigned long long bits) {
#if _MSC_VER >= 1920 || __INTEL_COMPILER
	return _mm_popcnt_u64(bits);
#else
	return __builtin_popcountll(bits);
#endif 
}

using R = long double;
using DD = pair<long double, Pi>;


int X[102];
int Y[102];


ll solve(int n) {
	vector<DD> z;
	rep(i, n) {
		int x = X[i];
		int y = Y[i];
		if (x == 0 && y == 0) {
			continue;
		}
		z.emplace_back(
			atan2((R)y, (R)x),
			Pi{ x,y }
		);
	}
	sort(z.begin(), z.end());
	ll ret2 = 0.0;
	rep(i, z.size()) {
		ll x = 0;
		ll y = 0;
		rep(j, z.size()) {
			x += z[(i + j) % z.size()].second.first;
			y += z[(i + j) % z.size()].second.second;
			ll d2 = x * x + y * y;
			ret2 = max(ret2, d2);
		}
	}
	return ret2;
}

ll solveB(const int n) {
	ll ret = 0;
	rep(i, 1 << n) {
		ll x = 0;
		ll y = 0;
		rep(j, n) {
			if ((i >> j) & 1) {
				x += X[j];
				y += Y[j];
			}
		}
		ll d2 = x * x + y * y;
		ret = max(ret, d2);
	}
	return ret;
}

uint32_t xor32 (void) {
	static uint32_t y = 2463534242;
	y = y ^ (y << 13); y = y ^ (y >> 17);
	return y = y ^ (y << 5);
}



void test() {
	const int n = 4;
	rep(cnt, INF) {
		rep(i, n) {
			X[i] = int(xor32() & 15) - 7;
			Y[i] = int(xor32() & 15) - 7;
		}
		/*
		rep(i, n) {
			cout << X[i] << " " << Y[i] << endl;
		}
		cerr << endl;
		//*/

		ll r0 = solve(n);
		ll r1 = solveB(n);

		if (r0 != r1) {
			PrtExpN(r0);
			PrtExpN(r1);
			rep(i, n) {
				cout << X[i] << " " << Y[i] << endl;
				exit(1);
			}
		}
		if ((cnt & 1023) == 0) {
			PrtExpN(cnt);
		}
	}

}

int main() {
	//test();

	int n;
	cin >> n;
	rep(i, n) {
		cin >> X[i] >> Y[i];
	}
	ll ret2 = solve(n);
	printf("%.19lf\n", sqrt((double)ret2));


}


Measured memory_bytes: 256