#pragma GCC optimize(2)
#include <bits/stdc++.h>
#define int long long
using namespace std;
int n, m, op, x, l, r, t[1000001],a[1000001],dp[1000001];
int read()
{
    int x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9')
    {
        if (ch == '-')
            f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9')
    {
        x = (x << 1) + (x << 3) + (ch ^ 48);
        ch = getchar();
    }
    return x * f;
}
signed main()
{
    n=read();
    for(int i=1;i<=n;i++)
    {
        t[i]=read();
    }
    for(int i=1;i<=n;i++)
    {
        a[i]=read();
        dp[i]=a[i]*t[i];
    }
    for(int i=1;i<=n;i++)
    {
        for(int j=i+t[i];j<=n;j++)
        {
            if(j-i>=t[j])
            {
                dp[j]=max(dp[j],dp[i]+a[j]*t[j]);
            }
            //cout<<j<<' '<<dp[j]<<endl;
        }
        //cout<<dp[i]<<endl;
    }
    printf("%lld",*max_element(dp+1,dp+n+1));
    return 0;
}