#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
auto read = [&]() {
string s;
cin >> s;
vector<int> res(n);
for (int i = 0; i < n; ++i) {
res[i] = s[i] - '0';
}
return res;
};
auto a = read();
auto b = read();
vector<vector<int>> dp(n, vector<int>(3, numeric_limits<int>::max()));
for (int x = 0; x < 3; ++x) {
int c = b[0] ^ (x == 2 ? a[0] : x);
dp[0][x] = c + (x != 2);
}
for (int i = 0; i < n - 1; ++i) {
for (int x = 0; x < 3; ++x) {
int xx = b[i] ^ (x == 2 ? a[i] : x);
for (int y = 0; y < 3; ++y) {
int yy = b[i + 1] ^ (y == 2 ? a[i + 1] : y);
dp[i + 1][y] = min(dp[i + 1][y], dp[i][x] + (y != x && y != 2) + (yy == 1 && xx == 0));
}
}
}
cout << *min_element(dp[n - 1].begin(), dp[n - 1].end()) << endl;
return 0;
}
