n = 100

function strategy(text)
  local lines = toLines(text)
  print("Lines found: " ..tostring(#lines))
  if #lines > n then
    local i1 = math.random(1, #lines-n)
    local i2 = i1+n
    print(table.concat(lines, "\n", i1, i2))
  end
end

function toLines(str)
  local t = {}
  local function helper(line) table.insert(t, line) return "" end
  helper((str:gsub("(.-)\r?\n", helper)))
  return t
end