#include <bits/stdc++.h>
using namespace std;
inline int ile(char a, char b, char c, char d) {
  if (a == c && b == d) return 0;
  if (a == d && b == c) return 0;
  if (a == b && c == d) return 0;
  if (a == c) return 1;
  if (a == d) return 1;
  if (b == c) return 1;
  if (b == d) return 1;
  if (c == d) return 1;
  return 2;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n;
  string A, B;
  cin >> n >> A >> B;
  int p = 0, k = n - 1;
  int w = 0;
  if ((n & 1) == 1 && (A[n >> 1] != B[n >> 1])) ++w;
  while (p < k) {
    w += ile(A[p], A[k], B[p], B[k]);
    ++p;
    --k;
  }
  cout << w;
  return 0;
}
