#include <bits/stdc++.h>
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define ll long long int
using namespace std;
int main() {
ll n; cin >> n; ll r = 0;
multiset<ll> x; deque<ll> y;
for (int i = 0; i < n; i++) {
ll xi; cin >> xi;
while (xi--) x.insert(i);
}
vector<ll> YY(n);
for (int i = 0; i < n; i++) cin >> YY[i];
for (int i = n-1; i >= 0; i--) {
while (y[i]--) {
if (x.lower_bound(i) == x.begin()) {
y.pb(i); continue;
}
x.erase(prev(x.lower_bound(i))); r++;
}
}
deque<ll> nx;
for (auto w : x) nx.pb(w);
for (int i = 0; i < y.size(); i++) {
if (y[i] < nx[i]) r--;
if (y[i] > nx[i]) r++;
}
cout << r;
return 0;
}
