#include <algorithm>
#include <iostream>
using namespace std;
const int N = 1000000;
const int INF = 0x3f3f3f3f;
char aa[N + 1], bb[N + 1];
int dp[2][2][3], dq[2][2][3];
int main() {
ios_base::sync_with_stdio(false), cin.tie(NULL);
int n; cin >> n >> aa >> bb;
for (int s = 0; s < 2; s++)
for (int t = 0; t < 2; t++)
for (int a = 0; a <= 2; a++)
dp[s][t][a] = INF;
dp[0][0][2] = 0;
for (int i = 0; i < n; i++) {
for (int s = 0; s < 2; s++)
for (int t = 0; t < 2; t++)
for (int a = 0; a <= 2; a++)
dq[s][t][a] = INF;
for (int s = 0; s < 2; s++)
for (int t = 0; t < 2; t++)
for (int a = 0; a <= 2; a++)
for (int s_ = 0; s_ < 2; s_++) {
int x = dp[s][t][a];
if (!s && s_)
x++;
int b = bb[i] - '0' ^ s_;
if (a != b) {
int t_ = t ^ 1;
dq[s_][t_][b] = min(dq[s_][t_][b], x + t + (a == 2));
} else
dq[s_][t][b] = min(dq[s_][t][b], x);
if (aa[i] - '0' == b)
dq[s_][0][2] = min(dq[s_][0][2], x);
}
for (int s = 0; s < 2; s++)
for (int t = 0; t < 2; t++)
for (int a = 0; a <= 2; a++)
dp[s][t][a] = dq[s][t][a];
}
int ans = INF;
for (int s = 0; s < 2; s++)
for (int t = 0; t < 2; t++)
for (int a = 0; a <= 2; a++)
ans = min(ans, dp[s][t][a]);
cout << ans << '\n';
return 0;
}
