#include <bits/stdc++.h> using namespace std; const long long mod = 1e9 + 7; const int MaxN = 1e6 + 5; int n; pair<long long, long long> arr[MaxN]; void Inp() { cin >> n; for (int x = 1; x <= n; x++) { cin >> arr[x].first; } for (int x = 1; x <= n; x++) { cin >> arr[x].second; } } int root; pair<int, int> child[MaxN]; void BuildTree() { for (int x = 1; x <= n; x++) { child[x] = make_pair(-1, -1); } stack<int> st; for (int x = 1; x <= n; x++) { int pre = -1; while (!st.empty() && arr[st.top()].first > arr[x].first) { pre = st.top(); st.pop(); } child[x].first = pre; if (!st.empty()) { child[st.top()].second = x; } else { root = x; } st.push(x); } } long long val[MaxN]; long long DFS(int u) { long long res = 0, a = (arr[u].first * (arr[u].first + 1) / 2) % mod, b = arr[u].second % mod; if (~child[u].first && ~child[u].second) { res = (res + DFS(child[u].first)) % mod; res = (res + DFS(child[u].second)) % mod; long long c = (val[child[u].first] + b) % mod, d = (val[child[u].second] + b) % mod; res = (res + c * d % mod * a % mod) % mod; res = (res - (arr[u].second * (arr[u].second - 1) / 2) % mod * a % mod) % mod; val[u] = (c + d - b) % mod; return res; } if (~child[u].first) { res = DFS(child[u].first); long long c = (val[child[u].first] + b) % mod; res = (res + c * b % mod * a % mod) % mod; res = (res - (arr[u].second * (arr[u].second - 1) / 2) % mod * a % mod) % mod; val[u] = c; return res; } if (~child[u].second) { res = DFS(child[u].second); long long c = (val[child[u].second] + b) % mod; res = (res + c * b % mod * a % mod) % mod; res = (res - (arr[u].second * (arr[u].second - 1) / 2) % mod * a % mod) % mod; val[u] = c; return res; } res = (arr[u].second * (arr[u].second + 1) / 2) % mod * a % mod; val[u] = b; return res; } void Exc() { BuildTree(); long long res = DFS(root); cout << (res % mod + mod) % mod; } int main() { //freopen("FANCYFENCE.INP", "r", stdin); //freopen("FANCYFENCE.OUT", "w", stdout); ios_base::sync_with_stdio(false); cin.tie(nullptr); int test = 1; //cin >> test; for (int x = 1; x <= test; x++) { Inp(); Exc(); } return 0; }