#include<iostream>
#include<cstdio>
#include<queue>
#define int long long int
using namespace std;
priority_queue<int> q;
int n,x[250001],y[250001],get=0,jl=0;
signed main()
{
	freopen("wing.in","r",stdin);
	freopen("wing.out","w",stdout);
	scanf("%lld",&n);
	for(int i=1;i<=n;i++)
	{
		scanf("%lld",&x[i]);
	} 
	for(int i=1;i<=n;i++)
	{
		scanf("%lld",&y[i]);
	}
	for(int i=1;i<=n;i++)
	{
		get+=x[i];
		if(get>=y[i])
		{
			get-=y[i];
			jl++;
			q.push(y[i]);
		}
		else
		{
			if(q.size()&&q.top()>y[i])
			{
				get+=q.top();
				q.pop();
				get-=y[i];
				q.push(y[i]);
			}
		}
	}
	printf("%lld",jl);
	return 0; 
}