local n = io.read("*n")
local m = io.read("*n")
local a = {}; do
  for i = 1, n do
    a[i] = io.read("*n")
  end
end

local ans = (function ()
  local gold = 0; do
    while true do
      if a[1] < m then
        break
      end

      local lack = false
      local generated = false
      do
        local i = 1
        for j = 2, n do
          if a[j] < m then
            if a[i] > m then
              a[i] = a[i] - 1
              a[j] = a[j] + 1
              generated = true
              break
            else
              lack = true
              break
            end
          end
          if a[j] > a[i] then
            i = j
          end
        end
      end

      if lack then
        break
      end

      if not generated then
        for i = 1, n do
          a[i] = a[i] - m
        end
        gold = gold + 1
      end
    end
  end
  return gold
end)()

print(ans)