local n = io.read("*n", "*l")
local a = {}
local b = {}
s = io.read()
for v in s:gmatch("%d") do
  table.insert(a, tonumber(v))
end
s = io.read()
for v in s:gmatch("%d") do
  table.insert(b, tonumber(v))
end
local t = {0}
for i = 1, n do
  if a[i] == b[i] then
    table.insert(t, i)
  end
end
table.insert(t, n + 1)
c = 0
for i = 1, #t - 1 do
  if 1 < t[i + 1] - t[i] then
    c = c + 1
  end
end
print(c)