#include <bits/stdc++.h>
using namespace std;
const int M = 1e6 + 10;
int n, ans;
void swap(int &x, int &y) {
  int t = x;
  x = y;
  y = t;
}
int main() {
  cin >> n;
  vector<char> x(n), y(n);
  for (auto &i : x) cin >> i;
  for (auto &i : y) cin >> i;
  for (int i = 0; i < n - 1; ++i) {
    if (x[i] == y[i]) continue;
    if (x[i + 1] == y[i + 1]) {
      ans++;
      continue;
    }
    if (x[i] == y[i + 1] && x[i + 1] == y[i])
      swap(x[i], x[i + 1]), ans++;
    else
      ans++;
  }
  if (x[n - 1] != y[n - 1]) ans++;
  cout << ans;
  return 0;
}
