#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pi pair<int, int>
#define vi vector<int>
#define vs vector<string>
#define vb vector<bool>
#define vpi vector<pi>
#define pb push_back
#define all(a) (a).begin(), (a).end()
const int mod = 1e9 + 7;
int md_inv_2 = 500000004;
int sm(int x)
{
return (((x * (x + 1)) % mod) * md_inv_2) % mod;
}
void solve()
{
int n;
cin >> n;
int h[n], w[n];
for (int i = 0; i < n; i++)
cin >> h[i];
int pref_w[n + 1];
pref_w[0] = 0;
for (int i = 0; i < n; i++)
{
cin >> w[i];
pref_w[i + 1] = (pref_w[i] + w[i]) % mod;
}
int curr = 0;
int ans = 0;
for (int i = 0; i < n; i++)
{
if (curr != h[i])
{
int w2 = (((pref_w[n] - pref_w[i]) % mod) + mod) % mod;
ans += (sm(w2) * (sm(h[i]) - sm(curr))) % mod;
curr = h[i];
}
}
cout << ans << '\n';
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
int t = 1;
// cin >> t;
while (t--)
{
solve();
}
return 0;
}
