#include <bits/stdc++.h>
using i64 = long long;
constexpr i64 mod = 1000000007;
i64 add(i64 a, i64 b) {
return (a + b) % mod;
}
i64 sub(i64 a, i64 b) {
return (a + mod - b) % mod;
}
i64 mul(i64 a, i64 b) {
return (a * b) % mod;
}
void eadd(i64 &a, i64 b) {
a = add(a, b);
}
void esub(i64 &a, i64 b) {
a = sub(a, b);
}
void emul(i64 &a, i64 b) {
a = mul(a, b);
}
i64 calcPaint(i64 x, i64 y) {
return mul((1 + x) * x / 2 % mod, (1 + y) * y / 2 % mod);
}
int main() {
int N;
std::cin >> N;
std::vector<i64> H(N), W(N);
for (auto &e : H) {
std::cin >> e;
}
for (auto &e : W) {
std::cin >> e;
}
if (std::all_of(H.begin(), H.end(), [&](auto x) {
return x == H[0];
})) {
// subtask 4
i64 X = H[0], Y = std::accumulate(W.begin(), W.end(), 0ll) % mod;
std::cout << calcPaint(X, Y) << std::endl;
return 0;
}
bool isSubtask5 = true;
for (int i = 1; i < N; ++i) {
if (H[i] < H[i - 1]) {
isSubtask5 = false;
}
}
if (isSubtask5) {
i64 wSum = 0, answer = 0;
for (int i = N - 1; i >= 0; --i) {
i64 a = calcPaint(H[i], wSum + W[i]), b = calcPaint(H[i], wSum);
esub(a, b);
eadd(answer, a);
wSum += W[i];
}
std::cout << answer << std::endl;
}
}
