#include <bits/stdc++.h>
using namespace std;
int solve(string from, string to) {
  int l = from.size();
  int ctr = 0;
  for (int i = 0; i < l; i++) {
    if (from[i] == to[i]) {
      continue;
    }
    if (i < l - 1) {
      if (from[i + 1] != from[i] && from[i + 1] != to[i + 1]) {
        ctr = ctr + 1;
        i++;
      } else {
        ctr = ctr + 1;
      }
    } else {
      ctr = ctr + 1;
    }
  }
  return ctr;
}
int main() {
  ios::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  int N;
  cin >> N;
  string from;
  string to;
  cin >> from;
  cin >> to;
  cout << solve(from, to);
  return 0;
}
