local mmi, mma = math.min, math.max
local mfl, mce = math.floor, math.ceil
local bls, brs = bit.lshift, bit.rshift
local Heapq = {}
Heapq.create = function(self, lt)
  self.lt = lt
  self.cnt = 0
  self.t = {}
end

Heapq.empty = function(self)
  return self.cnt == 0
end

Heapq.push = function(self, v)
  local hqlt = self.lt
  local hqt = self.t
  local c = self.cnt + 1
  self.cnt = c
  hqt[c] = v
  while 1 < c do
    local p = brs(c, 1)
    if hqlt(hqt[c], hqt[p]) then
      hqt[c], hqt[p] = hqt[p], hqt[c]
      c = p
    else
      break
    end
  end
end

Heapq.pop = function(self)
  local hqlt = self.lt
  local hqt = self.t
  local ret = hqt[1]
  local c = self.cnt
  hqt[1] = hqt[c]
  c = c - 1
  self.cnt = c
  local p = 1
  while true do
    local d1, d2 = p * 2, p * 2 + 1
    if c < d1 then break
    elseif c < d2 then
      if hqlt(hqt[d1], hqt[p]) then
        hqt[d1], hqt[p] = hqt[p], hqt[d1]
      end
      break
    else
      if hqlt(hqt[d1], hqt[d2]) then
        if hqlt(hqt[d1], hqt[p]) then
          hqt[d1], hqt[p] = hqt[p], hqt[d1]
          p = d1
        else break
        end
      else
        if hqlt(hqt[d2], hqt[p]) then
          hqt[d2], hqt[p] = hqt[p], hqt[d2]
          p = d2
        else break
        end
      end
    end
  end
  return ret
end

Heapq.new = function(lt)
  local obj = {}
  setmetatable(obj, {__index = Heapq})
  obj:create(lt)
  return obj
end

local n, m, p = io.read("*n", "*n", "*n")
local a = {}
local amax = 0
for i = 1, n do
  a[i] = io.read("*n")
  amax = mma(amax, a[i])
end
if m < amax then print(1) os.exit() end
local c = {}
for i = 1, n do
  local ci = 1
  local ai = a[i]
  while ai % p == 0 do
    ci = ci + 1
    ai = mfl(ai / p)
  end
  if 1 < ai then
    if c[ai] then
      c[ai] = mmi(c[ai], ci)
    else
      c[ai] = ci
    end
  end
end
if not next(c) then print(-1) os.exit() end
-- local cm = {}
-- for k, v in pairs(c) do
  -- table.insert(cm, {k, v})
-- end
-- table.sort(cm, function(a, b) return a[1] < b[1] end)
-- local cn = #cm

local val, score, valmap = {}, {}, {}
valmap[m] = 1
val[1] = m
score[1] = 0
local hq = Heapq.new(function(a, b) return val[a] > val[b] end)
hq:push(1)
local ret = 1000000007
while not hq:empty() do
  local idx = hq:pop()
  local v, s = val[idx], score[idx]
  if v < amax then
    ret = mmi(ret, s + 1)
  else
    for div, cost in pairs(c) do
    -- for i = 1, cn do
      -- local div = cm[i][1]
      -- local cost = cm[i][2]
      local dst = mfl(v / div)
      local dstidx = valmap[dst]
      if dstidx then
        score[dstidx] = mmi(score[dstidx], s + cost)
      else
        table.insert(val, dst)
        table.insert(score, s + cost)
        valmap[dst] = #val
        hq:push(#val)
      end
    end
  end
end
print(ret)
-- print(os.clock())