local ior = io.input()
local h, w = ior:read("*n", "*n", "*l")

local function getindex(i_h, i_w)
  return i_w + (i_h - 1) * w
end
local bsize = 2
local mapbox = {}
for i = 1, math.ceil(h * w / bsize) do
  mapbox[i] = 0
end
local function setval(idx, val)
  local boxidx = math.ceil(idx / bsize)
  local boxval = mapbox[boxidx]
  local newval, mul = 0, 1
  local boxpos = idx % bsize
  for i = 0, bsize - 1 do
    if(i == boxpos) then
      newval = newval + mul * (val % 2)
    else
      newval = newval + mul * (boxval % 2)
    end
    boxval = math.floor(boxval / 2)
    mul = mul * 2
  end
  mapbox[boxidx] = newval
end
local function getval(idx)
  local boxidx = math.ceil(idx / bsize)
  local boxval = mapbox[boxidx]
  local boxpos = idx % bsize
  for i = 1, boxpos do boxval = math.floor(boxval / 2) end
  return boxval % 2
end
local str = ""
for i_h = 1, h do
  str = ior:read()
  for i_w = 1, w do
    local idx = getindex(i_h, i_w)
    if(str:sub(i_w * 2 - 1, i_w * 2 - 1) == "1") then
      setval(idx, 1)
    else
      setval(idx, 0)
    end
  end
end

local tasks = {}
local tasknum = 0
local done = 0
local tasklim = h + w

local function addtask(idx)
  setval(idx, 0)
  tasknum = tasknum + 1
  local taskidx = tasknum % tasklim
  if taskidx == 0 then taskidx = tasklim end
  tasks[taskidx] = idx
end

local curpos = 1
local lakecount = 0
local function searchtask()
  for i = curpos, h * w do
    if(getval(i) == 1) then
      lakecount = lakecount + 1
      curpos = i
      addtask(i)
      break
    end
  end
end
searchtask()
while(done < tasknum) do
  done = done + 1
  local taskidx = done % tasklim
  if(taskidx == 0) then taskidx = tasklim end
  local idx = tasks[taskidx]
  if(w < idx) then if(getval(idx - w) == 1) then addtask(idx - w) end end
  if(idx <= (h - 1) * w) then if(getval(idx + w) == 1) then addtask(idx + w) end end
  if(1 < w) then
    if(idx % w ~= 0) then if(getval(idx + 1) == 1) then addtask(idx + 1) end end
    if(idx % w ~= 1) then if(getval(idx - 1) == 1) then addtask(idx - 1) end end
  end
  if(done == tasknum) then
    searchtask()
  end
end
print(lakecount)