#include <bits/stdc++.h>
using namespace std;
#define int ll
#define FOR(i,s,e) for(ll i = s; i <= (ll)e; ++i)
#define DEC(i,s,e) for(ll i = s; i >= (ll)e; --i)
#define IAMSPEED ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{" << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
#define reach cerr << "LINE: " << __LINE__ << "\n";
#else
#define db(x)
#define db2(x,y)
#define db3(a,b,c)
#define dbv(v)
#define dbvp(v)
#define dba(a,ss,ee)
#define reach
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define ll long long
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define f first
#define s second
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define g3(x) get<3>(x)
typedef pair <ll, ll> pi;
typedef tuple<ll,ll,ll> ti3;
typedef tuple<ll,ll,ll,ll> ti4;
ll rand(ll a, ll b) { return a + rng() % (b-a+1); }
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 500;
const long long oo = (ll)1e18 + 500;
template <typename T> void chmax(T& a, const T b) { a=max(a,b); }
template <typename T> void chmin(T& a, const T b) { a=min(a,b); }
const int MAXN = 1000005;
int n;
char A[MAXN];
char B[MAXN];
int dp[MAXN][3][2]; // {idx, operation 1/2, whether i want to flip}
int32_t main()
{
IAMSPEED
cin >> n;
FOR(i,1,n) cin >> A[i];
FOR(i,1,n) cin >> B[i];
FOR(i,0,MAXN-1)FOR(j,0,2)FOR(k,0,1)dp[i][j][k]=oo;
dp[0][0][0] = 0ll;
FOR(i,1,n) {
// do nothing
if(A[i] == B[i])dp[i][0][0] = min({dp[i-1][0][0], dp[i-1][0][1], dp[i-1][1][0], dp[i-1][1][1], dp[i-1][2][0], dp[i-1][2][1]});
//flip
if(A[i] != B[i]){
//reach
dp[i][0][1] = min({dp[i-1][0][0] + 1, dp[i-1][0][1], dp[i-1][1][0] + 1, dp[i-1][1][1], dp[i-1][2][0] + 1, dp[i-1][2][1]});
//db2(i-1,dp[i-1][0][0]);
}
//set to 0
if(B[i] == '0') dp[i][1][0] = min({dp[i-1][0][0] + 1, dp[i-1][0][1] + 1, dp[i-1][1][0], dp[i-1][1][1], dp[i-1][2][0] + 1, dp[i-1][2][1] + 1});
//set to 0 and flip
if(B[i] == '0') { //flip FIRST, then set
chmin(dp[i][1][1], dp[i-1][0][0] + 2);
chmin(dp[i][1][1], dp[i-1][0][1] + 1);
chmin(dp[i][1][1], dp[i-1][1][0] + 1);
if(B[i-1] == '0')chmin(dp[i][1][1], dp[i-1][1][1]);
else chmin(dp[i][1][1], dp[i-1][1][1] + 2);
chmin(dp[i][1][1], dp[i-1][2][0] + 2);
chmin(dp[i][1][1], dp[i-1][2][1] + 1);
} else { // set FIRST, then FLIP
chmin(dp[i][1][1], dp[i-1][0][0] + 2);
chmin(dp[i][1][1], dp[i-1][0][1] + 1);
chmin(dp[i][1][1], dp[i-1][1][0] + 1);
if(B[i-1] == '1')chmin(dp[i][1][1], dp[i-1][1][1]);
else chmin(dp[i][1][1], dp[i-1][1][1] + 2);
chmin(dp[i][1][1], dp[i-1][2][0] + 2);
chmin(dp[i][1][1], dp[i-1][2][1] + 1);
}
//set to 1
if(B[i] == '1') dp[i][2][0] = min({dp[i-1][0][0] + 1, dp[i-1][0][1] + 1, dp[i-1][1][0] + 1, dp[i-1][1][1] + 1, dp[i-1][2][0], dp[i-1][2][1]});
//set to 1 and flip
if(B[i] == '1') { //flip FIRST, then set
chmin(dp[i][2][1], dp[i-1][0][0] + 2);
chmin(dp[i][2][1], dp[i-1][0][1] + 1);
chmin(dp[i][2][1], dp[i-1][2][0] + 1);
if(B[i-1] == '1')chmin(dp[i][1][1], dp[i-1][2][1]);
else chmin(dp[i][2][1], dp[i-1][2][1] + 2);
chmin(dp[i][2][1], dp[i-1][1][0] + 2);
chmin(dp[i][2][1], dp[i-1][1][1] + 1);
} else { // set FIRST, then FLIP
chmin(dp[i][2][1], dp[i-1][0][0] + 2);
chmin(dp[i][2][1], dp[i-1][0][1] + 1);
chmin(dp[i][2][1], dp[i-1][2][0] + 1);
if(B[i-1] == '0')chmin(dp[i][1][1], dp[i-1][2][1]);
else chmin(dp[i][2][1], dp[i-1][2][1] + 2);
chmin(dp[i][2][1], dp[i-1][1][0] + 2);
chmin(dp[i][2][1], dp[i-1][1][1] + 1);
}
FOR(a,0,2) {
FOR(b,0,1) {
db(i);
db3(dp[i][a][b], a, b);
}
}
}
int res = oo;
FOR(i,0,2)FOR(j,0,1)chmin(res,dp[n][i][j]);
cout << res;
}
