#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;
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);
vector<ll> dp0(N+2,INF);
vector<ll> dpa(N+2,INF);
vector<ll> dpa2(N+2,INF);
vector<ll> dpa3(N+2,INF);
vector<ll> dpb(N+2,INF);
vector<ll> dpba(N+2,INF);
vector<ll> dpba2(N+2,INF);
vector<ll> dpba3(N+2,INF);
dp0[0]=0;
for (ll i=0;i<(N+1);i++) {
bool isa = va[i]^va[i+1];
bool isb = vb[i]^vb[i+1];
if (!isa && !isb) {
dp0[i+1]=dp0[i];
dpa[i+1]=dpa[i];
dpa2[i+1]=dpa2[i];
dpa3[i+1]=dpa3[i];
dpb[i+1]=dpb[i];
dpba[i+1]=dpba[i];
dpba2[i+1]=dpba2[i];
dpba3[i+1]=dpba3[i];
continue;
}
if (!isa && isb) {
dp0[i+1]=dp0[i]+1;
dpa[i+1]=dpa[i]+1;
dpa2[i+1]=dpa2[i]+1;
dpa3[i+1]=dpa3[i]+1;
dpb[i+1]=min(dpb[i]+1,dp0[i]+1);
dpba[i+1]=dpba[i]+1;
dpba2[i+1]=dpba2[i]+1;
dpba3[i+1]=dpba3[i]+1;
dp0[i+1]=min(dp0[i+1],dpba2[i]-1);
continue;
}
//else: isa
dp0[i+1]=dp0[i]+1;
dpa[i+1]=min(dp0[i]+1,dpa[i]+1);
dpa2[i+1]=min(min(dpa[i]+1,dpa2[i]+1),dpa3[i]-1);
dpa3[i+1]=min(dpa2[i]+1,dpa3[i]+1);
dpb[i+1]=dpb[i]+1;
dpba[i+1]=min(dpb[i]+1,dpba[i]+1);
dpba2[i+1]=min(min(dpba[i]+1,dpba2[i]+1),dpba3[i]-1);
dpba3[i+1]=min(dpba2[i]+1,dpba3[i]+1);
dp0[i+1]=min(dp0[i+1],dpba2[i]-1);
dp0[i+1]=min(dp0[i+1],dpa[i+1]);
dp0[i+1]=min(dp0[i+1],dpa2[i+1]);
dp0[i+1]=min(dp0[i+1],dpa3[i+1]);
dp0[i+1]=min(dp0[i+1],dpb[i+1]);
dp0[i+1]=min(dp0[i+1],dpba[i+1]);
dp0[i+1]=min(dp0[i+1],dpba2[i+1]);
dp0[i+1]=min(dp0[i+1],dpba3[i+1]);
//process isb
if (isb) {
dp0[i+1]++;
dpa[i+1]++;
dpa2[i+1]++;
dpa3[i+1]++;
dpb[i+1]++;
dpba[i+1]++;
dpba2[i+1]++;
dpba3[i+1]++;
dp0[i+1]=min(dp0[i+1],dp0[i]);
}
}
// for (ll i=0;i<(N+2);i++) {
// cout << "i="<<i<<"\n";
// cout << "dp0="<<dp0[i]<<"\n";
// cout << "dpa="<<dpa[i]<<"\n";
// cout << "dpa2="<<dpa2[i]<<"\n";
// cout << "dpa3="<<dpa3[i]<<"\n";
// cout << "dpb="<<dpb[i]<<"\n";
// cout << "dpba="<<dpba[i]<<"\n";
// cout << "dpba2="<<dpba2[i]<<"\n";
// cout << "dpba3="<<dpba3[i]<<"\n";
// }
cout << dp0[N+1]/2;
}
