local mmi, mma = math.min, math.max
local n = io.read("*n")
local p = {}
local pinv = {}
for i = 1, n do
  pinv[i] = 0
end
for i = 1, n do
  p[i] = io.read("*n")
  pinv[p[i]] = i
end
local ret = 0
local v = 0
for i = 1, n do v = v + i end
for i = n, 1, -1 do
  ret = mma(ret, v - pinv[i] * 2)
  v = v - pinv[i]
end
print(ret)