#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define bruh ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fu(x,a,b) for (auto x=a;x<=b;x++)
#define fd(x,a,b) for (auto x=a;x>=b;x--)
#define int ll
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
/*
Competitive Programming notes that I need to study & fix my dumbass self:
1. Coding:
- Always be sure to check the memory of arrays (maybe use vectors), for loops, I don't know
- Always try to maximize the memory if possible, even if you are going for subtasks
- Do not exploit #define int long long, it will kill you
2. Stress:
- Don't be cocky and think stressing with your dumbass brute-force solution will give you guaranteed AC.
- Always try generating big testcases and try if they run
3. Time management:
- Don't overcommit or undercommit, always spend a certain amount of time to think a problem, don't just look at it and say I'm fucked
- Do not spend too much time coding brute-force solutions, they should be easily-codable solutions that don't take up too much time
I hate offline because I am dumb
*/
typedef pair<int, int> ii;
const int N = 2e5+5;
const int mod = 1e9+7;
const int inf = 1e18;
using cd = complex<double>;
const long double PI = acos(-1);
int power(int a,int b) {ll x = 1;if (a >= mod) a%=mod; while (b) {if (b & 1) x = x*a % mod;a = a*a % mod;b>>=1;}return x;}
int n;
int h[N], w[N], pref[N];
int calc(int x, int y)
{
return ((x * (x+1) / 2ll) % mod) * ((y * (y+1) / 2ll) % mod) % mod;
}
void solve()
{
cin>>n;
for (int i = 1; i <= n; i++) cin>>h[i];
for (int i = 1; i <= n; i++) cin>>w[i], pref[i] = (pref[i-1] + w[i]) % mod;
stack<int> st;
st.push(0);
int ans = 0;
for (int i = 1; i <= n+1; i++)
{
while (!st.empty() && h[i] <= h[st.top()])
{
int pos = st.top();
st.pop();
if (st.empty()) break;
int x = h[pos] - max(h[i], h[st.top()]), y = (pref[i-1] - pref[st.top()] + mod) % mod;
int add = (calc(x,y) + (x * max(h[i], h[st.top()]) % mod) * (y * (y+1) / 2ll % mod) % mod) % mod;
ans = (ans + add) % mod;
}
st.push(i);
}
cout<<ans;
}
/*
Go through the mistakes you usually make and revise your code, for god's sake...
*/
signed main()
{
bruh
//freopen("input.inp","r",stdin);
//freopen("output.inp","w",stdout);
int t = 1;
// cin>>t;
while (t--)
{
solve();
cout<<"\n";
}
}
