local mce, mfl, msq, mmi, mma = math.ceil, math.floor, math.sqrt, math.min, math.max

local n = io.read("*n")
local a, b, c = {}, 0, {}
for i = 1, n do
  a[i], b = io.read("*n", "*n")
  c[i] = b - a[i]
end

local function dotask(stage, curtask)
  local nexttask = {}
  for i = 1, n do
    nexttask[i] = {}
  end
  for i = 1, n do
    for used, val in pairs(curtask[i]) do
      local tmp = used
      used = used + 1
      local mul = 1
      for j = 1, n do
        if tmp % 2 == 0 then
          local nt = nexttask[j][used]
          if nt then
            nexttask[j][used] = mmi(mma(val, c[i] + a[j]), nt)
          else
            nexttask[j][used] = mma(val, c[i] + a[j])
          end
        else
          tmp = tmp - 1
        end
        tmp = tmp / 2
        used = used + mul
        mul = mul * 2
      end
    end
  end
  return nexttask
end

local tasks = {}
local tmp = 1
for i = 1, n do
  tasks[i] = {}
  tasks[i][tmp] = 0
  tmp = tmp * 2
end
for i = 2, n do
  tasks = dotask(i, tasks)
end
local min = 1000 * 100
for i = 1, n do
  for k, v in pairs(tasks[i]) do
    min = mmi(min, v)
  end
end
print(min)