#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cmath>
#define ll long long
using namespace std;
inline ll read(){
	ll x=0,f=1;char ch=getchar();
	while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}
	while(ch<='9'&&ch>='0'){x=(x<<3)+(x<<1)+ch-'0';ch=getchar();}
	return x*f;
}
ll n,a[250010],b[250010];
void init(){
	freopen("wing.in","r",stdin);
	freopen("wing.out","w",stdout);
	memset(a,0,sizeof(a));
	memset(b,0,sizeof(b));
	n=read();
	for(int i=1;i<=n;i++)a[i]=read();
	for(int i=1;i<=n;i++)b[i]=read();
}
bool check(int x){
	int ans=0,ww=0;
	for(int i=1;i<=n;i++){
		ww+=a[i];
		if(ww>=b[i]){
			ans++;
			ww-=b[i];
		}
	}
	if(ans>=x)return 1;
	else return 0;
}
int main(){
	init();
	int l=0,r=250010;
	while(l+1<r){
		int mid=l+(r-l>>1);
		if(check(mid))l=mid;
		else r=mid;
	}
	if(check(l))printf("%d",l);
	else printf("%d",r);
	return 0;
}