#include "bits/stdc++.h"
#ifndef err
#define err(...)
#define DebugWriteLine(...)
#endif
using namespace std;
void Calc();
#define ALL(win) begin(win),end(win)
#define RALL(win) (win).rbegin(),(win).rend()
typedef int64_t ll;
typedef uint64_t ull;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
  cin.exceptions(istream::failbit | istream::badbit);
  Calc();
  cout.flush();
  return 0;
}
template<class T> struct Iter {
  T&operator++() { return ++i; }
  constexpr const T&operator*() const { return i; }
  constexpr bool operator!=(const Iter &o) const { return i != o.i; }
  T i;
};

struct Scanner {
  template<class A = string>static A Next() { A a; cin >> a; return a; }
  template<class A = int>static vector<A> Array(int n) { vector<A> a(n); for (A&i : a) cin >> i; return a; }
  static string Line() { string s; getline(cin, s); return s; }
  static int Int() { return Next<int>(); }
  template<class A>Scanner&operator,(A&a) { a = Next<A>(); return *this; }
  template<class A>operator A() { return Next<A>(); }
}in;

/*---------------------------------------------------------------------*/

void Calc() {
  int n = in;
  string s = in;
  string t = in;
  int cnt = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] != t[i])cnt++;
  }
  cout << cnt << endl;
}