import sys
from operator import itemgetter
import math

sys.setrecursionlimit(10 ** 8)

input = sys.stdin.readline


def main():
    N = int(input())
    XY = [[int(x) for x in input().split()] for _ in range(N)]

    ans = 0
    for i, (x, y) in enumerate(XY):
        if x == 0:
            katamuki = 0
            katamuki2 = float("inf")
        else:
            katamuki = y / x
            katamuki2 = -(x / y)
        plus = [0, 0]
        minus = [0, 0]
        plus2 = [0, 0]
        minus2 = [0, 0]
        for j, (xx, yy) in enumerate(XY):
            if i == j:
                continue
            if yy > katamuki * xx:
                plus[0] += xx
                plus[1] += yy
            else:
                minus[0] += xx
                minus[1] += yy

            if katamuki2 == float("inf"):
                if xx > 0:
                    plus2[0] += xx
                    plus2[1] += yy
                else:
                    minus2[0] += xx
                    minus2[1] += yy
            else:
                if yy > katamuki2 * xx:
                    plus2[0] += xx
                    plus2[1] += yy
                else:
                    minus2[0] += xx
                    minus2[1] += yy

        ans = max(ans, math.sqrt(plus[0] ** 2 + plus[1] ** 2))
        ans = max(ans, math.sqrt(minus[0] ** 2 + minus[1] ** 2))
        ans = max(ans, math.sqrt(plus2[0] ** 2 + plus2[1] ** 2))
        ans = max(ans, math.sqrt(minus2[0] ** 2 + minus2[1] ** 2))
        ans = max(ans, math.sqrt((plus[0] + x) ** 2 + (plus[1] + y) ** 2))
        ans = max(ans, math.sqrt((minus[0] + x) ** 2 + (minus[1] + y) ** 2))
        ans = max(ans, math.sqrt((plus2[0] + x) ** 2 + (plus2[1] + y) ** 2))
        ans = max(ans, math.sqrt((minus2[0] + x) ** 2 + (minus2[1] + y) ** 2))

    print(ans)


if __name__ == '__main__':
    main()


### FIXED CODE ###

import sys
from operator import itemgetter
import math

sys.setrecursionlimit(10 ** 8)

input = sys.stdin.readline


def main():
    N = int(input())
    XY = [[int(x) for x in input().split()] for _ in range(N)]

    ans = 0

    # x
    # plus, plus
    tmp = [0, 0]
    for x, y in XY:
        if x > 0:
            tmp[0] += x
            tmp[1] += y
        elif x == 0 and y > 0:
            tmp[0] += x
            tmp[1] += y

    ans = max(ans, math.sqrt(tmp[0] ** 2 + tmp[1] ** 2))

    # x
    # plus, minus
    tmp = [0, 0]
    for x, y in XY:
        if x > 0:
            tmp[0] += x
            tmp[1] += y
        elif x == 0 and y < 0:
            tmp[0] += x
            tmp[1] += y

    ans = max(ans, math.sqrt(tmp[0] ** 2 + tmp[1] ** 2))

    # x
    # minus, plus
    tmp = [0, 0]
    for x, y in XY:
        if x < 0:
            tmp[0] += x
            tmp[1] += y
        elif x == 0 and y > 0:
            tmp[0] += x
            tmp[1] += y

    ans = max(ans, math.sqrt(tmp[0] ** 2 + tmp[1] ** 2))

    # x
    # minus, minus
    tmp = [0, 0]
    for x, y in XY:
        if x < 0:
            tmp[0] += x
            tmp[1] += y
        elif x == 0 and y < 0:
            tmp[0] += x
            tmp[1] += y

    ans = max(ans, math.sqrt(tmp[0] ** 2 + tmp[1] ** 2))

    # y
    # plus, plus
    tmp = [0, 0]
    for x, y in XY:
        if y > 0:
            tmp[0] += x
            tmp[1] += y
        elif y == 0 and x > 0:
            tmp[0] += x
            tmp[1] += y

    ans = max(ans, math.sqrt(tmp[0] ** 2 + tmp[1] ** 2))

    # y
    # plus, minus
    tmp = [0, 0]
    for x, y in XY:
        if y < 0:
            tmp[0] += x
            tmp[1] += y
        elif y == 0 and x > 0:
            tmp[0] += x
            tmp[1] += y

    ans = max(ans, math.sqrt(tmp[0] ** 2 + tmp[1] ** 2))

    # y
    # minus, plus
    tmp = [0, 0]
    for x, y in XY:
        if y > 0:
            tmp[0] += x
            tmp[1] += y
        elif y == 0 and x < 0:
            tmp[0] += x
            tmp[1] += y

    ans = max(ans, math.sqrt(tmp[0] ** 2 + tmp[1] ** 2))

    # y
    # minus, minus
    tmp = [0, 0]
    for x, y in XY:
        if y < 0:
            tmp[0] += x
            tmp[1] += y
        elif y == 0 and x < 0:
            tmp[0] += x
            tmp[1] += y

    ans = max(ans, math.sqrt(tmp[0] ** 2 + tmp[1] ** 2))

    for i, (x, y) in enumerate(XY):
        if x == 0:
            katamuki = 0
            katamuki2 = float("inf")
        else:
            katamuki = y / x
            if y == 0:
                katamuki2 = float("inf")
            else:
                katamuki2 = -(x / y)
        plus = [0, 0]
        minus = [0, 0]
        plus2 = [0, 0]
        minus2 = [0, 0]
        for j, (xx, yy) in enumerate(XY):
            if i == j:
                continue
            if yy > katamuki * xx:
                plus[0] += xx
                plus[1] += yy
            else:
                minus[0] += xx
                minus[1] += yy

            if katamuki2 == float("inf"):
                if xx > 0:
                    plus2[0] += xx
                    plus2[1] += yy
                else:
                    minus2[0] += xx
                    minus2[1] += yy
            else:
                if yy > katamuki2 * xx:
                    plus2[0] += xx
                    plus2[1] += yy
                else:
                    minus2[0] += xx
                    minus2[1] += yy

        ans = max(ans, math.sqrt(plus[0] ** 2 + plus[1] ** 2))
        ans = max(ans, math.sqrt(minus[0] ** 2 + minus[1] ** 2))
        ans = max(ans, math.sqrt(plus2[0] ** 2 + plus2[1] ** 2))
        ans = max(ans, math.sqrt(minus2[0] ** 2 + minus2[1] ** 2))
        ans = max(ans, math.sqrt((plus[0] + x) ** 2 + (plus[1] + y) ** 2))
        ans = max(ans, math.sqrt((minus[0] + x) ** 2 + (minus[1] + y) ** 2))
        ans = max(ans, math.sqrt((plus2[0] + x) ** 2 + (plus2[1] + y) ** 2))
        ans = max(ans, math.sqrt((minus2[0] + x) ** 2 + (minus2[1] + y) ** 2))

    print(ans)


if __name__ == '__main__':
    main()