local mmi, mma = math.min, math.max
local n = io.read("*n", "*l")
local s = io.read()
local min, max = 0, 0
local sum = 0
local retmin, retmax = 0, 0
for i = 1, n do
  local a = io.read("*n")
  if s:sub(i, i) == "R" then a = -a end
  sum = sum + a
  retmin = mmi(retmin, sum - max)
  retmax = mma(retmax, sum - min)
  min = mmi(min, sum)
  max = mma(max, sum)
end
print(mma(math.abs(retmin), retmax))