#include <bits/stdc++.h>
using namespace std;
constexpr int MOD = 1e9 + 7;
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
int N; cin >> N;
vector<int> H(N), W(N);
for (auto &h: H) cin >> h;
for (auto &w: W) cin >> w;
vector<int> ps(N + 1);
for (int i = 0; i < N; i++) ps[i + 1] = (ps[i] + W[i]) % MOD;
int ans = 0;
stack<int> st;
for (int i = 0; i < N; i++) {
while (!st.empty() && H[st.top()] >= H[i]) {
int lst = st.top(); st.pop();
int max_h = H[lst];
int min_h = max(H[i], st.empty() ? 0 : H[st.top()]);
int dw = (ps[i] - (st.empty() ? 0 : ps[st.top() + 1]) + MOD) % MOD;
int wc = ((long long)dw * (dw + 1) / 2) % MOD;
int hc = ((long long)max_h * (max_h + 1) / 2 - (long long)min_h * (min_h + 1) / 2) % MOD;
int ch = (long long)wc * hc % MOD;
ans = (ans + ch) % MOD;
}
st.push(i);
}
while (!st.empty()) {
int lst = st.top(); st.pop();
int max_h = H[lst];
int min_h = st.empty() ? 0 : H[st.top()];
int dw = (ps.back() - (st.empty() ? 0 : ps[st.top() + 1]) + MOD) % MOD;
int wc = ((long long)dw * (dw + 1) / 2) % MOD;
int hc = ((long long)max_h * (max_h + 1) / 2 - (long long)min_h * (min_h + 1) / 2) % MOD;
int ch = (long long)wc * hc % MOD;
ans = (ans + ch) % MOD;
}
cout << ans << '\n';
}
