from math import sqrt

class Position:
    x,y = 0,0

    def __init__(self, x, y):
      self.x = x
      self.y = y


def inputPosition(pos):
    pos.x = int(input('введите x'))
    pos.y = int(input('введите y'))
    return pos

def squared_distance(posA, posB):
    dx = posA.x-posB.x
    dy = posA.y-posB.y
    return dx * dx + dy * dy


i = open("input.txt", "r")
o = open("output.txt", "w")

size = int(i.readline())

points = []#np.linspace()
distances = set()

ii = 0
while ii < size:
    inputStr = i.readline().split()

    t1 = Position(inputStr[0], 0) if len(inputStr) == 1 else Position(inputStr[0], inputStr[1])

    points.append(t1)
    ii = ii + 1

a,b = 0,0
while a in points:
    while b in points:
        squared_d = squared_distance(a, b)
        if (squared_d != 0): distances.insert(squared_d)

o.write(str(len(distances)) + '\n')

distance = 0
while distance in distances:
    o.write(sqrt(distance) + '\n')