#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
const int N = 1e6 + 7;
int dp[N][2][2][2];
int a[N], b[N];
const int Inf = 1e9 + 7;
bool valid(int i, int j, int k, int id) {
if (i == 1 && j == 1) return false;
int x = a[id];
if (i) x = 0;
if (j) x = 1;
if (k) x ^= 1;
return x == b[id];
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.setf(ios::fixed); cout.precision(20);
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
int n;
cin >> n;
for (int i = 0; i < n; ++i) {
char c;
cin >> c;
a[i] = c - '0';
}
for (int i = 0; i < n; ++i) {
char c;
cin >> c;
b[i] = c - '0';
}
for (int i = 0; i < N; ++i) {
for (int j = 0; j < 2; ++j) {
for (int k = 0; k < 2; ++k) {
for (int t = 0; t < 2; ++t) {
dp[i][j][k][t] = Inf;
}
}
}
}
dp[0][0][0][0] = 0;
for (int i = 0; i < n; ++i) {
for (int j = 0; j < 2; ++j) {
for (int k = 0; k < 2; ++k) {
for (int t = 0; t < 2; ++t) {
for (int nj = 0; nj < 2; ++nj) {
for (int nk = 0; nk < 2; ++nk) {
for (int nt = 0; nt < 2; ++nt) {
if (valid(nj, nk, nt, i)) {
int delta = (nj > j) + (nk > k) + (nt > t);
dp[i + 1][nj][nk][nt] = min(dp[i + 1][nj][nk][nt], dp[i][j][k][t] + delta);
}
}
}
}
}
}
}
}
int ans = Inf;
for (int i = 0; i < 2; ++i) for (int j = 0; j < 2; ++j) for (int k = 0; k < 2; ++k) ans = min(ans, dp[n][i][j][k]);
cout << ans << '\n';
}
