#include <iostream>
#include <vector>
#include <array>
#include <queue>
#define ll long long
using namespace std;
ll n, f = 1e18, dp[1000000][12];
string S, T;
ll get(ll u, vector <ll> state) {
ll mn = 1e18;
for (auto v : state) mn = min(mn, dp[u][v]);
return mn;
}
int main() {
cin.tie(0);
ios::sync_with_stdio(0);
cin >> n >> S >> T;
for (int i=0; i<n; ++i) {
for (int j=0; j<12; ++j) dp[i][j] = 1e18;
if (S[i] != T[i]) {
if (!i) dp[i][2] = 1;
else dp[i][2] = min(get(i-1, {2, 3, 4, 5, 6, 7, 8}), get(i-1, {0, 1, 9, 10, 11})+1);
}
else {
if (!i) dp[i][9] = 0;
else {
for (int j=0; j<12; ++j) {
dp[i][9] = min(dp[i][9], dp[i-1][j]);
}
}
}
if (T[i] == '0') {
if (!i) dp[i][0] = 1, dp[i][4] = dp[i][5] = dp[i][11] = 2, dp[i][8] = 3;
else {
dp[i][0] = min(get(i-1, {0, 3, 5, 7, 8, 10, 11}), get(i-1, {1, 2, 4, 6, 9})+1);
dp[i][4] = min(get(i-1, {4}), min(get(i-1, {1, 2, 3, 5, 6, 7, 8, 10, 11})+1, get(i-1, {0, 9})+2));
dp[i][5] = min(get(i-1, {5, 7, 8}), min(get(i-1, {0, 2, 3, 4, 6, 10, 11})+1, get(i-1, {1, 9})+2));
dp[i][8] = min(get(i-1, {8}), min(get(i-1, {5, 6, 7, 11})+1, min(get(i-1, {0, 1, 2, 3, 4, 10})+2, get(i-1, {9})+3)));
dp[i][11] = min(get(i-1, {8, 11}), min(get(i-1, {0, 1, 3, 4, 5, 6, 7, 10})+1, get(i-1, {2, 9})+2));
}
}
else {
if (!i) dp[i][1] = 1, dp[i][3] = dp[i][6] = dp[i][10] = 2, dp[i][7] = 3;
else {
dp[i][1] = min(get(i-1, {1, 4, 6, 7, 8, 10, 11}), get(i-1, {0, 2, 3, 5, 9})+1);
dp[i][3] = min(get(i-1, {3}), min(get(i-1, {0, 2, 4, 5, 6, 7, 8, 10, 11})+1, get(i-1, {1, 9})+2));
dp[i][6] = min(get(i-1, {6, 7, 8}), min(get(i-1, {1, 2, 3, 4, 5, 10, 11})+1, get(i-1, {0, 9}))+2);
dp[i][7] = min(get(i-1, {7}), min(get(i-1, {5, 6, 8, 10})+1, min(get(i-1, {0, 1, 2, 3, 4, 11})+2, get(i-1, {9})+3)));
dp[i][10] = min(get(i-1, {7, 10}), min(get(i-1, {0, 1, 3, 4, 5, 6, 8, 11})+1, get(i-1, {2, 9})+2));
}
}
}
for (int j=0; j<12; ++j) {
f = min(f, dp[n-1][j]);
}
cout << f << '\n';
}
