#include<bits/stdc++.h>
#include<fstream>
using namespace std;
#define sz(a) (int)a.size()
#define ALL(v) v.begin(), v.end()
#define ALLR(v) v.rbegin(), v.rend()
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
#define mpp make_pair
const ld PI = 3.14159265359, prec = 1e-9;;
//using u128 = __uint128_t;
//const int x[4] = {1, 0, -1, 0};
//const int y[4] = {0, -1, 0, 1};
const ll mod = 1e9 + 7, pr = 31;
const int mxn = 1e6 + 5, mxq = 1e5 + 5, sq = 500, mxv = 5e4 + 1;
//const int base = (1 <<18);
const ll inf = 1e9 + 5, neg = -69420, inf2 = 1e14;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
// have fun!
int n;
int dp[mxn + 1][3][2];
int a[mxn + 1], b[mxn + 1];
void ckmin(int &a, int b){
if(a > b)a = b;
}
void solve(){
cin >> n;
for(int i = 1; i <= n; i++){
char c; cin >> c; a[i] = (c - '0');
}
for(int i = 1; i <= n; i++){
char c; cin >> c; b[i] = (c - '0');
}
for(int i = 0; i <= n; i++){
for(int j = 0; j < 3; j++){
dp[i][j][0] = dp[i][j][1] = inf;
}
}
dp[0][0][0] = 0;
for(int i = 0; i < n; i++){
for(int j = 0; j < 3; j++){
for(int k = 0; k < 2; k++){
for(int l = 0; l < 3; l++){
for(int z = 0; z < 2; z++){
int bit;
if(l == 0)bit = a[i + 1];
else bit = l - 1;
if(z)bit = !bit;
if(bit == b[i + 1]){
ckmin(dp[i + 1][l][z], dp[i][j][k] + (j != l && l) + (k < z));
}
}
}
}
}
}
int ans = inf;
for(int i = 0; i < 3; i++){
for(int j = 0; j < 2; j++){
ckmin(ans, dp[n][i][j]);
}
}
cout << ans;
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//freopen("DATA.inp", "r", stdin);
//freopen("DATA.out", "w", stdout);
int tt; tt = 1;
while(tt--){
solve();
}
return(0);
}
