#include <bits/stdc++.h>
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
int n;
std::cin >> n;
std::string a, b;
std::cin >> a >> b;
auto f = [&](int i, int j) {
return i == n ? 0 : (j == 2 ? a[i] - '0' : j) ^ (b[i] - '0');
};
std::vector dp(n + 1, std::vector(3, std::vector<int>(2)));
dp[n][0][0] = dp[n][1][1] = dp[n][0][1] = dp[n][1][0] = 1e8;
for (int i = n - 1; i >= 0; --i) {
for (int k = 0; k < 2; ++k) {
dp[i][0][k] = std::min(
{dp[i + 1][0][k] + (f(i, 0) and !f(i + 1, 0)),
dp[i + 1][1][!k] + !k + (f(i, 0) and !f(i + 1, 1)),
dp[i + 1][2][0] + !k + (f(i, 0) and !f(i + 1, 2))});
dp[i][1][k] = std::min(
{dp[i + 1][0][!k] + !k + (f(i, 1) and !f(i + 1, 0)),
dp[i + 1][1][k] + (f(i, 1) and !f(i + 1, 1)),
dp[i + 1][2][0] + !k + (f(i, 1) and !f(i + 1, 2))});
dp[i][2][k] = std::min(
{dp[i + 1][0][1] + (f(i, 2) and !f(i + 1, 0)) + 1,
dp[i + 1][1][1] + (f(i, 2) and !f(i + 1, 1)) + 1,
dp[i + 1][2][0] + (f(i, 2) and !f(i + 1, 2))});
}
}
std::cout << std::min({dp[0][0][1] + 1, dp[0][1][1] + 1, dp[0][2][0]}) << '\n';
}
