#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using vll = vector<long long>;
using vvll = vector<vector<long long>>;
using vs = vector<string>;
#define lln \
  ll n;     \
  cin >> n;
#define REP(i, n) for (long long i = 0; i < n; i++)
#define REP2(i, s, e) for (long long i = s; i < e; i++)
#define UNIQUE_VECTOR(v) v.erase(unique(v.begin(), v.end()))
ll gcd(ll x, ll y) { return (x % y) ? gcd(y, x % y) : y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }

int main() {
  lln;
  string s, t;
  cin >> s >> t;
  string so, sr;
  so = s;
  reverse(s.begin(), s.end());
  sr = s;
  ll cnto = 0, cntr = 0;
  REP(i, n) {
    if (t[i] != so[i]) {
      cnto++;
    }
    if (t[i] != sr[i]) {
      cntr++;
    }
  }
  cout << min(cnto, cntr) << endl;
}

/*
0110111010
1001010011
@@@@@.@..@

0110111010
1100101001
@.@..@..@@
*/