#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e6 + 2;
const int inf = 1e9;
int dp[N][2][3], a[N], b[N];
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n; cin >> n;
string A, B;
cin >> A >> B;
for (int i = 0; i < n; i++) {
a[i + 1] = A[i] - '0';
b[i + 1] = B[i] - '0';
}
for (int i = 0; i <= n; i++) for (int j = 0; j < 6; j++) dp[i][j / 3][j % 3] = inf;
dp[0][0][0] = 0;
for (int i = 1; i <= n; i++) {
if (a[i] == b[i]) for (int j = 0; j < 6; j++) smin(dp[i][0][0], dp[i - 1][j / 3][j % 3]);
if (b[i] == 0) for (int j = 0; j < 6; j++) smin(dp[i][0][1], dp[i - 1][j / 3][j % 3] + (j % 3 != 1));
if (b[i] == 1) for (int j = 0; j < 6; j++) smin(dp[i][0][2], dp[i - 1][j / 3][j % 3] + (j % 3 != 2));
if (a[i] != b[i]) for (int j = 0; j < 6; j++) smin(dp[i][1][0], dp[i - 1][j / 3][j % 3] + (j < 3));
if (b[i] == 1) for (int j = 0; j < 6; j++) smin(dp[i][1][1], dp[i - 1][j / 3][j % 3] + (j % 3 != 1) + (j < 3));
if (b[i] == 0) for (int j = 0; j < 6; j++) smin(dp[i][1][2], dp[i - 1][j / 3][j % 3] + (j % 3 != 2) + (j < 3));
}
int ans = inf;
for (int j = 0; j < 6; j++) smin(ans, dp[n][j / 3][j % 3]);
cout << ans << en;
return 0;
}
