// 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], ans = 0, cur_len = 0, cur_sum = 0, iv = 0;
vector<array<long long, 3>> stk; // height, width, upper part
long long inv(long long a, long long b = MOD - 2)
{
long long ans = 1;
while (b > 0)
{
if (b & 1)
ans *= a;
a *= a;
ans %= MOD;
a %= MOD;
b >>= 1;
}
return ans;
}
void solve()
{
cin >> n;
iv = inv(2);
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();
int ch = a[0], cw = a[1], cd = a[2];
if (h[x] < ch)
{
cur_sum -= ((cur_len - cw) * iv) % MOD * (cd * (2 * ch - cd + 1)) % MOD;
cur_sum %= MOD;
stk.pop_back();
if (ch - cd > h[x])
{
continue;
}
else
{
cur_sum += ((cur_len - cw) * iv) % MOD * ((2 * h[x] - (h[x] - ch + cd) + 1) * (h[x] - ch + cd)) % MOD;
}
}
else
break;
cur_sum %= MOD;
}
if(cur_sum < 0) cur_sum += MOD;
long long i = 1;
i *= cur_sum * w[x];
i %= MOD;
i += ((w[x] * (w[x] + 1)) % MOD * iv) % MOD * ((h[x] * (h[x] + 1)) % MOD * iv) % MOD;
i %= MOD;
ans += i;
i = w[x];
i *= (((h[x]) * (h[x] + 1)) % MOD * iv) % MOD;
i %= MOD;
cur_sum += i;
if (stk.back()[0] != h[x])
{
stk.push_back({h[x], cur_len, h[x] - stk.back()[0]});
}
cur_len += w[x];
}
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;
}
