#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 1;
const int MOD = 1e9 + 7;
const int base = 257;
const int M = 1e6 + 1;
const int INFI = 1e8;
long long Hash[M], po[M];
long long gethash(long long l, long long r) {
  return ((Hash[r] - Hash[l - 1] * po[r - l + 1] + MOD * MOD) % MOD);
}
void precomputehashing() {
  po[0] = 1;
  for (int i = 1; i <= M; i++) po[i] = (po[i - 1] * base) % MOD;
  string s;
  s = " " + s;
  for (int i = 1; i <= s.size() - 1; i++)
    Hash[i] = (Hash[i - 1] * base + s[i] - '*' + 1) % MOD;
}
long long fac[N], ifac[N];
long long PowerMod(long long a, long long n) {
  long long ret = 1;
  while (n) {
    if (n & 1) {
      ret *= a;
      ret %= MOD;
    }
    a *= a;
    a %= MOD;
    n /= 2;
  }
  return ret;
}
void precomputecombinatoris() {
  int i;
  fac[0] = 1;
  for (i = 1; i < N; i++) {
    fac[i] = (i * fac[i - 1]) % MOD;
  }
  ifac[N - 1] = PowerMod(fac[N - 1], MOD - 2);
  for (i = N - 2; i >= 0; i--) {
    ifac[i] = ((i + 1) * ifac[i + 1]) % MOD;
  }
}
long long C(int r, int n) {
  long long ret = fac[n];
  ret *= ifac[r];
  ret %= MOD;
  ret *= ifac[n - r];
  ret %= MOD;
  return ret;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  a = ' ' + a;
  b = ' ' + b;
  for (int i = 1; i <= n / 2; i++) {
    if (a[i] != b[i]) {
      int j = n - i + 1;
      if ((a[i] == a[j] && b[i] == b[j]) || (a[i] == b[j] && b[i] == a[j])) {
        a[i] = b[i] = a[j] = b[j] = 'a';
        continue;
      }
      if (b[i] == b[j]) {
        swap(a[i], b[j]);
      }
      if (a[i] == b[j]) {
        swap(b[i], b[j]);
      }
      if (b[i] == a[j]) {
        swap(a[i], a[j]);
      }
    }
  }
  int res = 0;
  for (int i = 1; i <= n; i++) {
    if (a[i] != b[i]) {
      res++;
    }
  }
  cout << res;
  return 0;
}
