#include<bits/stdc++.h>
const int N = 1e6 + 5;
const int inf = 1e9 + 7;
using namespace std;
string s, x;
int n, dp[N][3][2], ans = inf;
char cal(char c, int i, int j){
if (i != 2) c = i + '0';
if (j) c = '1' + '0' - c;
return c;
}
void up(int&a, int b){
if (a > b) a = b;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> s >> x; s = '.' + s; x = '.' + x;
for (int i = 0; i < N; i++) for (int j = 0; j < 3; j++) for (int k = 0; k < 2; k++) dp[i][j][k] = inf;
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 (cal(s[i], 0, k) == x[i]) up(dp[i][0][k], dp[i-1][j][k] + (j != 0));
if (cal(s[i], 1, k) == x[i]) up(dp[i][1][k], dp[i-1][j][k] + (j != 1));
if (cal(s[i], 2, k) == x[i]) up(dp[i][2][k], dp[i-1][j][k]);
if (cal(s[i], 0, k ^ 1) == x[i]) up(dp[i][0][k ^ 1], dp[i-1][j][k] + (j != 0) + (k == 0));
if (cal(s[i], 1, k ^ 1) == x[i]) up(dp[i][1][k ^ 1], dp[i-1][j][k] + (j != 1) + (k == 0));
if (cal(s[i], 2, k ^ 1) == x[i]) up(dp[i][2][k ^ 1], dp[i-1][j][k] + (k == 0));
}
}
}
for (int i = 0; i < 3; i++) for (int j = 0; j < 2; j++) up(ans, dp[n][i][j]);
cout << ans;
}
