#include <bits/stdc++.h>
#define eb emplace_back
#define printv(a, b) { \
for(auto pv : a) b << pv << " "; \
b << "\n"; \
}
using namespace std;
int gettype(vector<int>& now){
int n = now.size();
int diff = 0;
for(int i = 0; i < n; i++){
if(now[i] == 1) diff++;
}
if(diff == 0) return 3;
else if(diff == n) return 2;
int l = 0, r = 0;
for(int i = 0; i < n && now[i] == 1; i++) l++;
for(int i = n - 1; i >= 0 && now[i] == 1; i--) r++;
if(l + r != diff) return 4;
if(r == 0) return 5;
if(l == 0) return 6;
return 1;
}
vector<int> v;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
string a, b;
cin >> n >> a >> b;
a += ' ';
b += ' ';
vector<int> now;
char lst = 0;
int ans = 0;
for(int i = 0; i <= n; i++){
if(i != 0 && b[i] != lst && !now.empty()){
int t = gettype(now);
now.clear();
if(t == 4) ans++;
else v.eb(t);
}
lst = b[i];
now.eb(a[i] != b[i]);
}
int m = v.size();
//printv(v, cerr);
//printv(del, cerr);
bool tmp = false;
for(int i = 0; i < m; i++){
if(v[i] == 1){
ans++;
}
if(v[i] == 2){
tmp = true;
}
if(v[i] == 3){
if(tmp) ans++;
tmp = false;
}
if(v[i] == 5){
ans++;
tmp = false;
}
if(v[i] == 6){
if(tmp) ans++;
tmp = true;
}
}
if(tmp) ans++;
cout << ans << "\n";
return 0;
}
