#include <bits/stdc++.h>
using namespace std;
using vi = basic_string<int>;
#define range(x) (x).begin(), (x).end()
#define bs(v, x) upper_bound(range(v), x) - (v).begin()
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
int n;
cin >> n;
int sx = 0;
vi x(n,0), y(n,0), xl, py(n, 0);
for(int i=0; i<n; i++){
cin >> y[i];
if(i){
py[i] = py[i-1];
}
py[i] += y[i];
}
for(int i=0; i<n; i++){
cin >> x[i];
sx += x[i];
if(sx > 1000000) return 0;
for(int j=0; j<x[i]; j++){
xl += i;
}
}
auto ty = y;
int ans = 0, typ = 0;
deque<int> d1, d2;
for(int i=0; i<sx; i++){
while(!(ty[typ])) typ++;
if(typ < xl[i]){
ans++;
}
else if(typ == xl[i]){
d1.push_back(i);
}
else{
d2.push_back(i);
ans--;
}
ty[typ]--;
}
int answer = ans;
for(int i=1; i<=sx; i++){
//cerr << i << ':' << '\n';
//cerr << ans << ' ' << d2.front() << ':' << bs(py, d2.front() - i) << ' ' << d1.front() << ':' << bs(py, d1.front() - i) << '\n';
if(xl[i-1] > bs(py, 0)){
ans -= 2;
}
else if(xl[i-1] == bs(py, 0)){
ans -= 1;
}
while(d2.size() && d2.front() < i){
d2.pop_front();
}
//cerr << "d2\n";
while(d2.size() && xl[d2.front()] >= bs(py, d2.front() - i)){
//cerr << d2.front() << ' ' << bs(py, d2.front() - i) << '\n';
ans++;
d1.push_back(d2.front());
d2.pop_front();
}
while(d1.size() && d1.front() < i){
d1.pop_front();
}
//cerr << "d1\n";
while(d1.size() && xl[d1.front()] > bs(py, d1.front() - i)){
//cerr << d1.front() << ' ' << bs(py, d1.front() - i) << '\n';
ans++;
d1.pop_front();
}
if(ans > answer){
answer = ans;
}
}
cout << answer;
return 0;
}
