#include <bits/stdc++.h>
using namespace std;
#define int long long
#define form2(i, a, b) for (int i = (a); i < (b); ++i)
#define ford2(i, a, b) for (int i = (a-1); i >= (b); --i)
#define form(i, n) form2(i, 0, n)
#define ford(i, n) ford2(i, n, 0)
#define chmax(x, v) x = max(x, (v))
#define chmin(x, v) x = min(x, (v))
#define fi first
#define se second
const long long BIG = 1000000000000000000LL;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
void solve();
signed main()
{
ios::sync_with_stdio(false);
cin.tie(0);
solve();
return 0;
}
const int borne = 1000*1000 + 5;
int dp[borne][2][3];
int len;
int cur[borne];
int cible[borne];
void calc(int dep, int isToggle, int set)
{
int &rep = dp[dep][isToggle][set];
rep = BIG;
if (dep) {
int vc = cur[dep];
if (set < 2) vc = set;
if (isToggle) vc ^= 1;
if (vc != cible[dep]) { rep = BIG; return; }
}
if (dep == len) { rep = 0; return; }
form(newTog, 2) form(newSet, 3) {
int cx = dp[dep+1][newTog][newSet];
if (newTog == 1 && isToggle == 0) ++cx;
if (newSet != set && newSet != 2) ++cx;
chmin(rep, cx);
}
}
void solve()
{
cin >> len;
string s, t;
cin >> s >> t;
form(i, len) cur[i+1] = (s[i] == '0' ? 0 : 1);
form(i, len) cible[i+1] = (t[i] == '0' ? 0 : 1);
ford(i, len) form(a, 2) form(b, 3) calc(i+1,a,b);
calc(0, 0, 2);
cout << dp[0][0][2] << "\n";
}
