#include<bits/stdc++.h>
#include<ext/pb_ds/tree_policy.hpp>
#include<ext/pb_ds/assoc_container.hpp>
#define ll long long
#define int long long
using namespace std;

const int maxd = 20;
const int maxn = 510000;

int n;
int c[maxn],a[maxn];

int rmq[maxd][maxn];
void build()
{
	for(int i=1;i<=n;i++) rmq[0][i]=c[i];
	for(int d=1;(1<<d)<=n;d++)
	{
		for(int i=1;i+(1<<d)-1<=n;i++)
		{
			rmq[d][i]= max( rmq[d-1][i], rmq[d-1][i+(1<<(d-1))] );
		}
	}
}
int query(int l,int r)
{
	int len=r-l+1;
	int d= 31-__builtin_clz(len);
	return max( rmq[d][l], rmq[d][r-(1<<d)+1] );
}
/*
int seg[maxn<<2];
void build(const int x,const int l,const int r)
{
	if(l==r)
	{
		seg[x]=c[l];
		return;
	}
	int mid=(l+r)>>1,lc=x<<1,rc=lc|1;
	build(lc,l,mid); build(rc,mid+1,r);
	seg[x]=max(seg[lc],seg[rc]);
}
int lx,rx;
int query(const int x,const int l,const int r)
{
	if(rx<l||r<lx) return -1;
	if(lx<=l&&r<=rx) return seg[x];
	int mid=(l+r)>>1,lc=x<<1,rc=lc|1;
	return max(query(lc,l,mid),query(rc,mid+1,r));
}*/
ll f[maxn];

int q[maxn],qc[maxn],head,tail;

int calc(int i,int j)
{
	int l=j+1,r=n;
	while(l<=r)
	{
		int mid=(l+r)>>1;
		if( f[i] + query(i+1,mid)*(mid-i) >= f[j] + query(j+1,mid)*(mid-j) ) r=mid-1;
		else l=mid+1;
	}
	return r+1;
}

signed main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	/*
	cerr<<31-__builtin_clz(1)<<endl;
	cerr<<31-__builtin_clz(2)<<endl;
	cerr<<31-__builtin_clz(3)<<endl;
	cerr<<31-__builtin_clz(4)<<endl;
	*/
	cin>>n;
	for(int i=1;i<=n;i++) cin>>c[i];
	build();
	for(int i=1;i<n;i++) cin>>a[i];
	a[0]=a[n]=0;
	
	f[0]=0;
	q[ head=tail=1 ]=0;
	for(int i=1;i<=n;i++)
	{
		while(head<tail && i>=qc[head]) head++;
		int j=q[head];
		f[i]=f[j]+ a[i] + query(j+1,i)*(i-j);
		
		q[++tail]=i;
		while(head<tail)
		{
			if(f[q[tail-1]]>=f[q[tail]]) q[tail-1]=q[tail],tail--;
			else
			{
				qc[tail-1]=calc(q[tail-1],q[tail]);
				if(head+2<=tail && qc[tail-2]>=qc[tail-1]) q[tail-1]=q[tail],tail--;
				else break;
			}
		}
	}
	
	cout<<f[n]<<endl;
	
	return 0;
}