#include <bits/stdc++.h>
using namespace std;

#define ll long long

const ll mod = 1e9 + 7;

void solve() {
    ll n;
    cin >> n;
    vector<ll> height(n, 0);
    vector<ll> width(n, 0);
    for(ll &x : height) cin >> x;
    for(ll &x : width) cin >> x;
    ll cur_height = 0;
    ll cur_width = 0;
    ll ans = 0;
    for(ll i = n - 1; i >= 0; --i) {
        cur_width += width[i];
        cur_height = height[i];
        ll cur_ans = 1;
        cur_ans *= (cur_width * width[i] - ((width[i] * (width[i] - 1)) / 2));
        cur_ans %= mod;
        cur_ans *= (cur_height * (cur_height + 1)) / 2;
        cur_ans %= mod;
        ans += cur_ans;
        ans %= mod;
    }
    cout << ans << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}