// IamHereForFun //
#include <bits/stdc++.h>
using namespace std;
#define LSOne(X) ((X) & -(X))
const int N = 1e5 + 5;
const int M = 1e6 + 5;
const int C = 26;
const int LG = 20;
const int R = 25e3 + 5;
const int B = 100;
const int O = 3e5 + 5;
const int INF = 1e9 + 5;
const int MOD = 1e9 + 7;
const int nx[] = {0, 1, 0, -1}, ny[] = {1, 0, -1, 0};
long long n, h[N], w[N];
long long cur_sum = 0, cur_len = 0, ans = 0;
vector<array<long long, 3>> stk;
long long cal(long long h, long long w)
{
long long a = h * (h + 1) / 2;
a %= MOD;
a *= (w * (w + 1) / 2) % MOD;
return a;
}
void solve()
{
cin >> n;
for (int x = 0; x < n; x++)
{
cin >> h[x];
}
for (int x = 0; x < n; x++)
{
cin >> w[x];
}
stk.push_back({0, 0, 0});
for (int x = 0; x < n; x++)
{
while (!stk.empty())
{
array<long long, 3> a = stk.back();
if (a[0] > h[x])
{
if (a[0] - a[1] > h[x])
{
cur_sum -= cal(a[1], a[2]);
stk.pop_back();
}
else
{
cur_sum -= cal(a[0] - h[x], a[2]);
stk.pop_back();
stk.push_back({h[x], h[x] - a[1], a[2]});
}
}
else
break;
}
cur_sum %= MOD;
cur_sum += MOD;
cur_sum %= MOD;
cur_len += w[x];
if (stk.back()[0] != h[x])
{
stk.push_back({h[x], h[x] - stk.back()[0], cur_len});
}
ans += cal(h[x], w[x]) + cur_sum*w[x];
cur_sum += w[x] * ((h[x] * (h[x] + 1) / 2) % MOD);
cur_sum %= MOD;
ans %= MOD;
// cout << ans << " " << cur_sum << "\n";
}
cout << ans;
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
for (int x = 1; x <= t; x++)
{
solve();
}
return 0;
}
