#include <bits/stdc++.h>
using namespace std;
const int ON0 = 1;
const int ON1 = 0;
const int OFF = 2;
const int MAX_N = 1e6;
int initial[MAX_N + 1], corect[MAX_N + 1];
int dp[MAX_N + 1][3][2];
int main() {
int n;
string a, b;
cin >> n >> a >> b;
initial[0] = corect[0] = 0;
for ( int i = 0; i < n; i++ ) {
initial[i + 1] = a[i] - '0';
corect[i + 1] = b[i] - '0';
}
for ( int i = 0; i <= n; i++ ) {
for ( int s = 0; s < 3; s++ ) {
for ( int b = 0; b < 2; b++ )
dp[i][s][b] = n;
}
}
dp[0][OFF][0] = 0;
for ( int i = 1; i <= n; i++ ) {
//OFF
for ( int s = 0; s < 3; s++ ) {
dp[i][OFF][initial[i]] = min( dp[i][OFF][initial[i]], dp[i - 1][s][corect[i - 1]] + (initial[i] != corect[i]) ); //era corect
dp[i][OFF][initial[i]] = min( dp[i][OFF][initial[i]], dp[i - 1][s][corect[i - 1] ^ 1] ); //era gresit
}
//ON0
for ( int s = 0; s < 3; s++ ) {
dp[i][ON0][0] = min( dp[i][ON0][0], dp[i - 1][s][corect[i - 1]] + (s != ON0) + (corect[i] != 0) ); //era corect
dp[i][ON0][0] = min( dp[i][ON0][0], dp[i - 1][s][corect[i - 1] ^ 1] + (s != ON0) ); //era gresit
}
//ON1
for ( int s = 0; s < 3; s++ ) {
dp[i][ON1][1] = min( dp[i][ON1][1], dp[i - 1][s][corect[i - 1]] + (s != ON1) + (corect[i] != 1) ); //era corect
dp[i][ON1][1] = min( dp[i][ON1][1], dp[i - 1][s][corect[i - 1] ^ 1] + (s != ON1) ); //era gresit
}
}
int minn = MAX_N;
for ( int s = 0; s < 3; s++ ) {
for ( int b = 0; b < 2; b++ )
minn = min( minn, dp[n][s][b] );
}
cout << minn;
return 0;
}
