local mmi, mma = math.min, math.max
local mfl, mce = math.floor, math.ceil
local mesh = 100
local lim = 201
local t = {}
for i = 1, lim do
  t[i] = {}
  for j = 1, lim do
    t[i][j] = {}
  end
end
local function inner(a, b, c, d)
  return (a - c) * (a - c) + (b - d) * (b - d) < 400
end
local n = io.read("*n")
for _i = 1, n do
  local a, b = io.read("*n", "*n")
  a = a + 1
  b = b + 1
  local ap = mce(a / mesh)
  local bp = mce(b / mesh)
  local imin = mma(1, ap - 1)
  local imax = mmi(lim, ap + 1)
  local jmin = mma(1, bp - 1)
  local jmax = mmi(lim, bp + 1)
  local found = false
  for i = imin, imax do for j = jmin, jmax do
    local tbl = t[i][j]
    for k = 1, #tbl do
      local c, d = tbl[k][1], tbl[k][2]
      if inner(a, b, c, d) then found = true break end
    end
    if found then break end
  end if found then break end end
  if not found then
    table.insert(t[ap][bp], {a, b})
  end
end
local ret = 0
for i = 1, lim do for j = 1, lim do
  ret = ret + #t[i][j]
end end
print(ret)