#include<bits/stdc++.h>
#define ll long long
#define ldb long double
#define fi first
#define se second
#define pir pair<int,int>
using namespace std;
const int maxn = 1e6 + 5;
int dp[maxn],lst[maxn][3],nxt[maxn];
bool a[maxn],b[maxn];
void input(int n){
string s;
cin >> s;
for (int i = 1 ; i <= n ; i++)
a[i] = s[i - 1] - 48;
cin >> s;
for (int i = 1 ; i <= n ; i++)
b[i] = s[i - 1] - 48;
}
void prepare(int n){
for (int id = 0 ; id <= 3 ; id++)
for (int i = 0 ; i <= n ; i++) lst[i][id] = -1;
for (int i = 0 ; i <= n ; i++) nxt[i] = -1;
for (int i = 1 ; i <= n ; i++){
//lst[0]
if (b[i])
lst[i][0] = -1;
else
lst[i][0] = (lst[i - 1][0] == -1) ? i : lst[i - 1][0];
if (!b[i])
lst[i][1] = -1;
else
lst[i][1] = (lst[i - 1][1] == -1) ? i : lst[i - 1][1];
if (a[i] == b[i])
lst[i][2] = -1;
else
lst[i][2] = (lst[i - 1][2] == -1) ? i : lst[i - 1][2];
if (a[i] != b[i])
nxt[i] = -1;
else
nxt[i] = (nxt[i - 1] == -1) ? i : nxt[i - 1];
}
for (int i = 1 ; i <= n ; i++) dp[i] = n + 1;
}
void solve(int n){
for (int i = 1 ; i <= n ; i++){
for (int id = 0 ; id <= 2 ; id++)
if (lst[i][id] != -1)
dp[i] = min(dp[i],dp[lst[i][id] - 1] + 1);
if (nxt[i] != -1)
dp[i] = min(dp[i],dp[nxt[i] - 1]);
if (lst[i][2] != -1){
//xor
int p = lst[i][2] - 1;
if (lst[p][0] != -1){
int p1 = lst[p][0] - 1;
if (a[p1] != b[p1])
dp[i] = min(dp[i],dp[p1] + 1);
}
if (lst[p][1] != -1){
int p1 = lst[p][1] - 1;
if (a[p1] != b[p1])
dp[i] = min(dp[i],dp[p1] + 1);
}
}
dp[i] = min(dp[i],dp[i - 1] + 1);
}
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
int n;
cin >> n;
input(n);
prepare(n);
solve(n);
cout << dp[n];
return 0;
}
