//Segment Tree is a State of Mind
#include <bits/stdc++.h>
using namespace std;
#define debug(x) cerr<<#x<<" is "<<x<<endl;
#define debugl(x) cerr <<'\n'<< #x << " is "; for(auto p : x) cerr << p << " "; cerr << endl;
#define int long long
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef pair<int,pii> ipii;
#define pb push_back
#define fi first
#define se second
#define sz(x) (int)(x).size()
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);
//mt19937_64 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
int n;cin>>n;
deque<int> dq;
vi v;
for(int i=0;i<n;i++){
int x;cin>>x;
if(x)dq.pb(i);
}
for(int i=0;i<n;i++){
int x;cin>>x;
if(x)v.pb(i);
}
while(sz(dq)>sz(v))dq.pop_back();
int nc=0,s=0;
for(auto i:v){
if(dq[0]<i){
dq.pop_front();
s++;
continue;
}
if(nc>0){
dq.pop_back();
nc--;
}else{
if(dq[0]==i){
nc++;
dq.pop_front();
}else{
dq.pop_back();
s--;
}
}
}
cout<<s<<'\n';
}
