#include <bits/stdc++.h>
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
const int inf = 1e8;
int n;
std::cin >> n;
std::string a, b;
std::cin >> a >> b;
auto range = [&](int s, int e, int t) {
int ans = 0;
int zca = 0, oca = 0;
char prev_b = b[s];
for (int i = s; i <= e; ++i) {
if (b[i] != prev_b) {
if (t == 1) {
std::swap(zca, oca);
}
if (prev_b == '0') {
ans += oca > 0;
} else {
ans += zca > 0;
}
zca = oca = 0;
}
zca += a[i] == '0', oca += a[i] == '1';
prev_b = b[i];
}
if (t == 1) {
std::swap(zca, oca);
}
if (prev_b == '0') {
ans += oca > 0;
} else {
ans += zca > 0;
}
zca = oca = 0;
return ans;
};
std::vector dp(n + 1, std::vector(n + 1, std::vector<int>(2)));
for (int i = n; i >= 0; --i) {
for (int b = n; b >= 0; --b) {
for (int t = 0; t < 2; ++t) {
if (i == n) {
dp[i][b][t] = i == b ? 0 : inf;
continue;
}
dp[i][b][t] = std::min(dp[i + 1][i + 1][1 - t] + range(b, i, t) + t,
dp[i + 1][b][t]);
}
}
}
std::cout << std::min(dp[0][0][0], dp[0][0][1]) << '\n';
}
