#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "deb.h"
#else
#define debug(...)
#endif
#define pb emplace_back
#define all(a) (a).begin(), (a).end()
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define sz(a) (int) (a).size()
using vi = vector<int>;
using ll = long long;
const int inf = int(1e9);
void solve() {
int n;
cin >> n;
string a, b;
cin >> a >> b;
a = '$' + a;
b = '$' + b;
auto Get = [&](char c, int state) {
if (state == 0) {
return '0';
} else if (state == 1) {
return '1';
} else {
return c;
}
};
vector<vi> dp(n + 1, vi(3, inf));
dp[0][2] = 0;
rep(i, n + 1) {
rep(cur, 3) {
rep(prev, 3) {
if (i == 0) {
continue;
}
int v = dp[i - 1][prev];
if (cur != prev && cur != 2) {
v++;
}
if ((i == 1 || Get(a[i - 1], prev) == b[i - 1]) && (Get(a[i], cur) != b[i])) {
v++;
}
dp[i][cur] = min(dp[i][cur], v);
}
}
}
cout << *min_element(dp[n].begin(), dp[n].end()) << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int t = 1;
// cin >> t;
while (t--) {
solve();
}
return 0;
}
