#include <bits/stdc++.h>
using i64 = long long;
constexpr int P = 1E9 + 7, two = (P + 1) / 2;
i64 norm(i64 x) {
if (x >= P) {
x -= P;
} else if (x < 0) {
x += P;
}
return x;
}
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int n;
std::cin >> n;
std::vector<i64> h(n + 1), w(n + 1);
for (int i = 1; i <= n; i++) {
std::cin >> h[i];
}
for (int i = 1; i <= n; i++) {
std::cin >> w[i];
w[i] += w[i - 1];
}
std::vector<std::pair<i64, i64>> s;
s.emplace_back(0, 0);
i64 a = 0;
i64 ans = 0;
for (int i = 1; i <= n; i++) {
while (s.back().first >= h[i]) {
i64 x = (s.back().second - s[int(s.size()) - 2].second) % P;
a = norm(a - x * (s.back().first * (s.back().first + 1) / 2 % P) % P);
s.pop_back();
}
if (s.back().second != w[i - 1]) {
i64 x = (w[i - 1] - s.back().second) % P;
a = norm(a + x * (h[i] * (h[i] + 1) / 2 % P) % P);
s.emplace_back(h[i], w[i - 1]);
}
i64 x = (w[i] - w[i - 1]) % P;
i64 y = h[i];
ans = norm(ans + a % P * x % P);
ans = norm(ans + (x * (x + 1) % P * two % P) * (y * (y + 1) % P * two % P) % P);
a = norm(a + (h[i] * (h[i] + 1) / 2 % P) * x % P);
s.emplace_back(h[i], w[i]);
}
std::cout << ans << "\n";
return 0;
}
