local mmi, mma = math.min, math.max
local mab = math.abs
local bls, brs = bit.lshift, bit.rshift
local bxor = bit.bxor
local xb, yb = io.read("*n", "*n")
local n = io.read("*n")
local x, y, w = {}, {}, {}
for i = 1, n do
  x[i], y[i], w[i] = io.read("*n", "*n", "*n")
end
local wsum = {}
local tot = bls(1, n)
for i = 1, tot do
  local ti = i - 1
  local ws = 0
  for j = 1, n do
    if ti % 2 == 1 then
      ws = ws + w[j]
    end
    ti = brs(ti, 1)
  end
  wsum[i] = ws
end
local len = {}
for i = 1, n do
  len[i] = {}
  for j = 1, n do
    len[i][j] = mab(x[i] - x[j]) + mab(y[i] -y[j])
  end
end

local alltask = {}
local stagetask = {}
for i = 1, n do
  alltask[i] = {}
  stagetask[i] = {}
end
for i = 1, n do
  for j = 1, tot - 1 do
    -- set inf value
    alltask[i][j] = 1000000007
  end
end
for i = 1, tot - 1 do
  local ti = i
  local cnt = 0
  for j = 1, n do
    if ti % 2 == 1 then
      cnt = cnt + 1
      ti = ti - 1
    end
    ti = ti / 2
  end
  table.insert(stagetask[cnt], i)
end
-- set first state
for i = 1, n do
  local v = mab(xb - x[i]) + mab(yb - y[i])
  alltask[i][bls(1, i - 1)] = v * (wsum[tot] + 100) / 120 + w[i]
end
do
  for stage = 1, n - 1 do
    local stlen = #stagetask[stage]
    for i_stagetask = 1, stlen do
      local used = stagetask[stage][i_stagetask]
      local rem = bxor(tot - 1, used)
      local rem_w = wsum[rem + 1]
      local t_used = used
      for i = 1, n do
        if t_used % 2 == 1 then
          local val = alltask[i][used]
          local mul = 1
          local tmp = used
          for j = 1, n do
            if tmp % 2 == 0 then
              local v = len[i][j] * (rem_w + 100) / 120 + w[j]
              alltask[j][used + mul] = mmi(alltask[j][used + mul], val + v)
              -- alltask[j][used + mul] = val + func(from i to j)
            else
              tmp = tmp - 1
            end
            tmp = tmp / 2
            mul = mul * 2
          end
          t_used = t_used - 1
        end
        t_used = t_used / 2
      end
    end
  end
end

local ret = 1000000007
for i = 1, n do
  local l = mab(xb - x[i]) + mab(yb - y[i])
  ret = mmi(ret, alltask[i][tot - 1] + l * 100 / 120)
end
print(string.format("%.10f", ret))