#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  cin >> N;
  string a, b;
  cin >> a >> b;
  int total = 0;
  for (int i = 0; i < a.size(); i++)
    if (a[i] != b[i]) {
      if (i + 1 < a.size() && a[i + 1] == b[i] && a[i] == b[i + 1])
        swap(a[i], a[i + 1]);
      else
        a[i] = b[i];
      total += 1;
    }
  cout << total << endl;
}
