#include <bits/stdc++.h>
using namespace std;
long long int power(long long int a, long long int b) {
  long long int res = 1;
  a %= 1000000007;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % 1000000007;
    a = a * a % 1000000007;
  }
  return res;
}
long long int modInverse(long long int a) { return power(a, 1000000007 - 2); }
const int N = 100001;
bool vis[N];
vector<int> adj[N];
long long int gcd(long long int a, long long int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long int lcm(long long int a, long long int b) {
  return a * b / gcd(a, b);
}
void solve() {
  long long int n;
  cin >> n;
  string a;
  string b;
  cin >> a >> b;
  long long int count = 0;
  for (long long int i = 0; i < n; i++) {
    if (a[i] != b[i]) {
      if ((i != n - 1) && (a[i + 1] != b[i + 1]) && (a[i] != a[i + 1])) {
        count++;
        i++;
      } else {
        count++;
      }
    }
  }
  cout << count << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int T = 1;
  int t = 0;
  while (t++ < T) {
    solve();
  }
  cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC
       << "ms\n";
}
