#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 10;
const int INF = 1e9;
string s1, s2;
int n, dp[N][3][2], ans = INF;
char f(char c, int i, int j){
if (i != 2) c = i + '0';
if (j) c = '1' + '0' - c;
return c;
}
int main() {
ios:: sync_with_stdio(0), cin.tie(0);
cin >> n >> s1 >> s2;
s1 = 'D' + s1; s2 = 'D' + s2;
memset(dp, 63, sizeof dp);
dp[0][2][0] = 0;
for (int i = 1; i <= n; i++)
for (int j = 0; j < 3; j++)
for (int k = 0; k < 2; k++) {
if (f(s1[i], 0, k) == s2[i]) dp[i][0][k] = min(dp[i][0][k], dp[i-1][j][k] + (j != 0));
if (f(s1[i], 1, k) == s2[i]) dp[i][1][k] = min(dp[i][1][k], dp[i-1][j][k] + (j != 1));
if (f(s1[i], 2, k) == s2[i]) dp[i][2][k] = min(dp[i][2][k], dp[i-1][j][k]);
if (f(s1[i], 0, k ^ 1) == s2[i]) dp[i][0][k ^ 1] = min(dp[i][0][k ^ 1], dp[i - 1][j][k] + (j ^ 0) + !(k ^ 0));
if (f(s1[i], 1, k ^ 1) == s2[i]) dp[i][1][k ^ 1] = min(dp[i][1][k ^ 1], dp[i - 1][j][k] + (j ^ 1) + !(k ^ 0));
if (f(s1[i], 2, k ^ 1) == s2[i]) dp[i][2][k ^ 1] = min(dp[i][2][k ^ 1], dp[i - 1][j][k] + !(k ^ 0));
if (i == n) ans = min(ans, dp[i][j][k]);
}
cout << ans << '\n';
}
