#include <bits/stdc++.h>
using namespace std;
using ll = long long; using pii = pair<ll,ll>;
const ll INF = 1e18;
int main() {
ios_base::sync_with_stdio(false); cin.tie(0);
ll N; cin >> N;
string A,B; cin >> A >> B;
ll ans = 0;
vector<bool> va,vb;
va.push_back(0); vb.push_back(0);
for (ll i=0;i<N;i++) {
va.push_back(A[i]=='1');
vb.push_back(B[i]=='1');
}
va.push_back(0); vb.push_back(0);
set<ll> vda,vdb;
for (ll i=0;i<(va.size()-1);i++) {
if (va[i]^va[i+1]) {
vda.insert(i);
}
if (vb[i]^vb[i+1]) {
vdb.insert(i);
}
}
vda.insert(-1); vdb.insert(-1);
vda.insert(2000000); vdb.insert(2000000);
vector<ll> vcom;
for (ll x0: vda) {
if (vdb.find(x0)!=vdb.end()) {
vcom.push_back(x0);
}
}
ll K = vcom.size();
ll dp[K]; //double the answer
dp[0]=0;
for (ll i=1;i<K;i++) {
dp[i]=INF;
}
for (ll i=1;i<K;i++) {
for (ll j=max(i-4,0LL);j<i;j++) {
//cout << "i,j="<<i<<","<<j<<"\n";
vector<ll> vta,vtb;
for (auto A0 = vda.upper_bound(vcom[j]);A0!=vda.end() && (*A0)<vcom[i];A0++) {
vta.push_back((*A0));
}
for (auto A0 = vdb.upper_bound(vcom[j]);A0!=vdb.end() && (*A0)<vcom[i];A0++) {
vtb.push_back(*A0);
}
// for (ll x0: vta) {
// cout << "vta: "<<x0 <<"\n";
// }
// for (ll x0: vtb) {
// cout << "vtb: "<<x0 <<"\n";
// }
ll dpt = vtb.size()+(vta.size()%2);
if (vta.size()<=1) {
//cout << "set: "<<(dp[j]+dpt)<< "\n";
dp[i]=min(dp[i],dp[j]+dpt);
continue;
}
dpt+=2;
//cout << "set: "<<(dp[j]+dpt)<< "\n";
dp[i]=min(dp[i],dp[j]+dpt);
if (vtb.size()==0) {
continue;
}
ll amin = vtb[0]; ll amax = vtb[vtb.size()-1];
ll nbtw = 0;
ll nlb = 0;
ll nub = 0;
for (ll x0: vta) {
if (x0>=amin && x0<=amax) {
nbtw++;
}
if (x0>=amin) {
nlb++;
}
if (x0<=amax) {
nub++;
}
}
if ((nub == vta.size() || nlb == vta.size())&&vta.size()%2==1) {
//cout << "f1\n";
//cout << "set: "<<(dp[j]+dpt-2)<< "\n";
dp[i]=min(dp[i],dp[j]+dpt-2);
continue;
}
if ((nbtw == (vta.size()) && vta.size()%2==0) || (nbtw >= (vta.size()-1) && vta.size()%2==1)) {
//cout << "f2\n";
//cout << "set: "<<(dp[j]+dpt-2)<< "\n";
dp[i]=min(dp[i],dp[j]+dpt-2);
continue;
}
}
}
cout << (dp[K-1]/2);
}
