local n, m = io.read("*n", "*n")
local l, r = {}, {}
local idx = {}
for i = 1, m do
  l[i], r[i] = io.read("*n", "*n")
  idx[i] = i
end
table.sort(idx, function(a, b)
  if r[a] == r[b] then
    return l[a] < l[b]
  else
    return r[a] < r[b]
  end
end)
local c = 0
local mark = 0
for ti = 1, m do
  local i = idx[ti]
  if mark < l[i] then
    c = c + 1
    mark = r[i]
  end
end
print(n - c)