#include <bits/stdc++.h>
#define chmin(x, v) x = min(x, v)
using namespace std;
const int TAILLE_CHAINE = 1e6 + 1;
int dp[TAILLE_CHAINE][3][2];
int lenChaine;
bool depart[TAILLE_CHAINE], arrivee[TAILLE_CHAINE];
string d, a;
void litEntree();
void solve();
int main()
{
litEntree();
solve();
return 0;
}
void litEntree()
{
cin >> lenChaine;
cin.ignore();
getline(cin, d);
for (int idCara = 0; idCara < lenChaine; ++idCara){
depart[idCara] = d[idCara] - '0';
// cout << depart[idCara];
}
//cin.ignore();
getline(cin, a);
for (int idCara = 0; idCara < lenChaine; ++idCara)
arrivee[idCara] = a[idCara] - '0';
for (int i = 0; i < lenChaine; ++i)
for (int j = 0; j < 3; ++j)
for (int k = 0; k < 2; ++k)
dp[i][j][k] = 1e6 + 5;
}
void solve()
{
for (int idCara = 0; idCara < lenChaine; ++idCara)
{
if (idCara == 0)
{
if (depart[idCara] == arrivee[idCara])
dp[idCara][2][0] = 0;
else
dp[idCara][2][1] = 1;
dp[idCara][arrivee[idCara]][0] = dp[idCara][arrivee[idCara]][1] = 1;
dp[idCara][arrivee[idCara]][1]++;
}
else
{
chmin(dp[idCara][arrivee[idCara]][0], dp[idCara - 1][arrivee[idCara]][0]);
chmin(dp[idCara][arrivee[idCara]][0], dp[idCara - 1][arrivee[idCara]][1]);
chmin(dp[idCara][arrivee[idCara]][0], dp[idCara - 1][!arrivee[idCara]][0] + 1);
chmin(dp[idCara][arrivee[idCara]][0], dp[idCara - 1][!arrivee[idCara]][1] + 1);
chmin(dp[idCara][arrivee[idCara]][0], dp[idCara - 1][2][0] + 1);
chmin(dp[idCara][arrivee[idCara]][0], dp[idCara - 1][2][1] + 1);
chmin(dp[idCara][arrivee[idCara]][1], dp[idCara - 1][arrivee[idCara]][0] + 1);
chmin(dp[idCara][arrivee[idCara]][1], dp[idCara - 1][arrivee[idCara]][1]);
chmin(dp[idCara][arrivee[idCara]][1], dp[idCara - 1][!arrivee[idCara]][0] + 2);
chmin(dp[idCara][arrivee[idCara]][1], dp[idCara - 1][!arrivee[idCara]][1] + 1);
chmin(dp[idCara][arrivee[idCara]][1], dp[idCara - 1][2][0] + 2);
chmin(dp[idCara][arrivee[idCara]][1], dp[idCara - 1][2][1] + 1);
for (int idDelta = 0; idDelta < 3; ++idDelta)
for (int idChange = 0; idChange < 2; ++ idChange)
{
if (arrivee[idCara] == depart[idCara])
chmin(dp[idCara][2][0], dp[idCara - 1][idDelta][idChange]);
else
chmin(dp[idCara][2][1], dp[idCara - 1][idDelta][idChange] + 1 - idChange);
}
}
/*cout << "-------\n";
for (int i = 0; i < 3; ++i){
for (int j = 0; j < 2; ++j)
cout << dp[idCara][i][j] << " ";
cout << endl;
}
cout << "---\n";*/
}
int mini = 1e6 + 10;
for (int i = 0; i < 3; ++i)
for (int j = 0; j < 2; ++j)
chmin(mini, dp[lenChaine - 1][i][j]);
cout << mini << endl;
}
