#include <bits/stdc++.h>
#include <ostream>
#define pb push_back
#define s second
#define f first
#define pb push_back
#define pii pair <int,int>
#define ll long long
#define left h*2,l,(l + r)/2
#define right h*2+1,(l + r)/2 + 1,r
#define int ll
using namespace std;
const int N = 1e6 + 5,inf = 1e9;
int dp[N][5][5];
signed main() {
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int n;
cin>>n;
string A;
cin>>A;
string B;
cin>>B;
A = '$' + A;
B = '%' + B;
for (int i = 0; i <= n; i++)
for (int j = 0; j < 4; j++)
for (int k = 0; k < 4; k++)
dp[i][j][k] = inf;
dp[0][0][0] = 0;
for (int i = 1; i <= n; i++){
for (int j = 0; j < 4; j++){
for (int k = 0; k < 4; k++){
if (dp[i - 1][j][k] == inf) continue;
for (int j1 = 0; j1 < 4; j1++){
for (int k1 = 0; k1 < 4; k1++){
if (!j1 && k1) continue;
if (j1 == k1 && j1) continue;
int val = (A[i] - '0');
if (j1 == 1) val = 1;
if (j1 == 2) val = 0;
if (j1 == 3) val ^= 1;
if (k1 == 1) val = 1;
if (k1 == 2) val = 0;
if (k1 == 3) val ^= 1;
int f = (B[i] - '0');
if (val != f) continue;
int c = 0;
if (j1 && k1){
if (j1 == j && k1 == k) c = 0;
else if (j1 == k && k1 == j) c = 1;
else {
if (j1 != j && j1 != k) c++;
if (k1 != j && k1 != k) c++;
}
}else {
if (j1 && j1 != k && j1 != j) ++c;
}
dp[i][j1][k1] = min(dp[i][j1][k1],c + dp[i - 1][j][k]);
}
}
}
}
}
int ans = inf;
for (int j = 0; j < 4; j++)
for (int k = 0; k < 4; k++)
ans=min(ans,dp[n][j][k]);
cout<<ans<<endl;
}
