#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define NL "\n"
#define SP " "
#define fmax(a, b) a = max(a, b)
#define fmin(a, b) a = min(a, b)
#define all(v) v.begin(), v.end()
const int mn = 1e6 + 1;
int dp[mn][3][2][3];
bool A[mn], B[mn];
int cost1 (int a, int b) {
if (b == 0 || a == b) return 0;
return 1;
}
int cost2 (int a, int b) {
if (b == 2 || a == b) return 0;
return 1;
}
void update (int i, int j, int k, int l) {
for (int j2 = 0; j2 < 3; j2++) {
for (int k2 = 0; k2 < 2; k2++) {
for (int l2 = 0; l2 < 3; l2++) {
if (dp[i - 1][j2][k2][l2] == INT_MAX) continue;
dp[i][j][k][l] = min(dp[i][j][k][l], dp[i - 1][j2][k2][l2] + cost2(j2, j) + cost1(k2, k) + cost2(l2, l));
}
}
}
return;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
int n; cin >> n;
for (int i = 1; i <= n; i++) {
char c; cin >> c;
if (c == '1') A[i] = 1;
}
for (int i = 1; i <= n; i++) {
char c; cin >> c;
if (c == '1') B[i] = 1;
}
for (int i = 0; i <= n; i++) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 2; k++) {
for (int l = 0; l < 3; l++) dp[i][j][k][l] = INT_MAX;
}
}
}
dp[0][2][0][2] = 0;
for (int i = 1; i <= n; i++) {
// xor
update(i, !B[i], 1, 2);
update(i, 0, 1, B[i]);
update(i, 1, 1, B[i]);
update(i, 2, 1, B[i]);
if (A[i] != B[i]) update(i, 2, 1, 2);
// not xor
update(i, B[i], 0, 2);
update(i, 0, 0, B[i]);
update(i, 1, 1, B[i]);
update(i, 2, 1, B[i]);
if (A[i] == B[i]) update(i, 2, 0, 2);
}
int ans = INT_MAX;
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 2; k++) {
for (int l = 0; l < 3; l++) ans = min(ans, dp[n][j][k][l]);
}
}
cout << ans;
return 0;
}
