local ffi = require("ffi")
local C = ffi.C
ffi.cdef[[
long long atoll(const char*);
]]

local function lltonumber(str)
  return C.atoll(str)
end

local n = lltonumber(io.read())
local min = 1LL
local max = 1000000007LL
while 1LL < max - min do
  local mid = (min + max) / 2LL
  if mid * mid <= n then
    min = mid
  else
    max = mid
  end
end
if min * min == n then
  local ret = tostring(min * 2LL - 1LL):gsub("LL", "")
  print(ret)
else
  local ret = tostring(min * 2LL):gsub("LL", "")
  print(ret)
end