#include <bits/stdc++.h>
using namespace std;
inline bool isvowel(char c) {
  c = tolower(c);
  if (c == 'a' || c == 'e' || c == 'i' || c == 'y' || c == 'o' || c == 'u')
    return 1;
  return 0;
}
const double eps = 0.000001;
const long double pi = acos(-1);
const int maxn = 1e7 + 9;
const int mod = 1e9 + 7;
const long long MOD = 1e18 + 9;
const long long INF = 1e18 + 123;
const int inf = 2e9 + 11;
const int mxn = 1e6 + 9;
const int N = 6e5 + 123;
const int M = 22;
const int pri = 997;
const int Magic = 2101;
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};
int n, m, k;
int cnt[N];
string s, t;
int a[N];
vector<int> g[N];
int u[N];
int ans, res;
int cur;
int main() {
  cin >> n >> s >> t;
  for (long long i = 0; i <= n - 1; i++) {
    if (s[i] != t[i]) {
      if (s[i + 1] == t[i] && s[i] == t[i + 1]) {
        ans++;
        i++;
        continue;
      }
      ans++;
    }
  }
  cout << ans;
  return 0;
}
