#include <bits/stdc++.h>
using namespace std;
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
#define ll long long
#define ld long double
#define all(a) (a).begin(), (a).end()
#define sui cout.tie(NULL); cin.tie(NULL); ios_base::sync_with_stdio(false)
const int MAX_N = 1e5 + 5;
const int MOD = 1e9 + 7;
const ll INF = 1e9;
const ld EPS = 1e-9;
const int LOG = 30;
void solve() {
int n;
cin >> n;
string a, b;
cin >> a >> b;
int dp[n + 1][2][2];
for (int i = 0; i < 2; i++) for (int j = 0; j < 2; j++) dp[n][i][j] = 0;
for (int i = n - 1; i >= 0; i--)
{
for (int j = 0; j < (i == 0 ? 1 : 2); j++) for (int k = 0; k < (i == 0 ? 1 : 2); k++)
{
dp[i][j][k] = INF;
int num = -1;
if (k) num = (j ? 1 - (b[i - 1] - '0') : b[i - 1] - '0');
for (int p = 0; p < 2; p++) for (int pp = 0; pp < 2; pp++)
{
int num1 = a[i] - '0';
int num2 = -1;
if (pp) num1 = num2 = (p ? 1 - (b[i] - '0') : b[i] - '0');
if (p) num1 ^= 1;
if (num1 != b[i] - '0') continue;
if (k == 0) dp[i][j][k] = min(dp[i][j][k], (p == 1 && j == 0) + pp + dp[i + 1][p][pp]);
else if (pp) dp[i][j][k] = min(dp[i][j][k], (p == 1 && j == 0) + (num2 != num) + dp[i + 1][p][pp]);
else dp[i][j][k] = min(dp[i][j][k], (p == 1 && j == 0) + dp[i + 1][p][pp]);
}
// cout << i << " " << j << " " << k << " " << dp[i][j][k] << " " << num << endl;
}
}
cout << dp[0][0][0] << "\n";
}
int main() {
sui;
int tc = 1;
//cin >> tc;
for (int t = 1; t <= tc; t++) {
solve();
}
}
