#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define f first
#define s second
#define pb push_back
#define ep emplace
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define uniquev(v) sort(all(v)), (v).resize(unique(all(v)) - (v).begin())
#define mem(f,x) memset(f , x , sizeof(f))
#define sz(x) (ll)(x).size()
#define __lcm(a, b) (1ll * ((a) / __gcd((a), (b))) * (b))
#define mxx *max_element
#define mnn *min_element
#define cntbit(x) __builtin_popcountll(x)
#define len(x) (int)(x.length())
const int N = 1e6 + 100;
int f[N][3];
string a, b;
char get(int x, int y) {
if (y == 1)
return '0';
if (y == 2)
return '1';
return a[x];
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
//freopen("LIGHTS.inp", "r", stdin);
//freopen("LIGHTS.out", "w", stdout);
mem(f, 0x3f);
int n;
cin >> n;
cin >> a >> b;
f[0][0] = (a[0] != b[0]);
f[0][1] = (int)(b[0] != '0') + 1;
f[0][2] = (int)(b[0] != '1') + 1;
for (int i = 1; i < n; i++) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 3; k++) {
char s1 = get(i - 1, j), s2 = get(i, k);
int d1 = s1 != b[i - 1], d2 = s2 != b[i];
f[i][k] = min(f[i][k], f[i - 1][j] + (d1 == 0 && d2 == 1) + (k != j && k));
}
}
}
cout << min({f[n - 1][0], f[n - 1][1], f[n - 1][2]}) << '\n';
return 0;
}
