#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int const MOD = 1e9 + 7;
int n;
vector<ll> h, w;
void read() {
cin >> n;
h.resize(n);
w.resize(n);
for (auto &a : h) cin >> a;
for (auto &a : w) cin >> a;
}
ll modsub(ll a, ll b) {
ll ret = (a - b) % MOD;
if (ret < 0) ret += MOD;
return ret;
}
ll pot(ll a, int k) {
ll ret = 1;
while (k) {
if (k % 2) {
ret *= a;
ret %= MOD;
}
a *= a;
a %= MOD;
k /= 2;
}
return ret;
}
void solve() {
read();
h.push_back(0);
w.push_back(0);
ll ans = 0;
ll inv2 = pot(2, MOD - 2);
vector<pair<ll, ll>> stck;
h.push_back(0);
w.push_back(0);
stck.emplace_back(0, 0);
for (int i = 0; i <= n; ++i) {
ll sumW = 0;
while (stck.back().first > h[i]) {
ll prevH = max(h[i], stck[stck.size() - 2].first);
ll dH = stck.back().first - prevH;
sumW = (sumW + stck.back().second) % MOD;
stck.pop_back();
ans += (dH * (dH + 1) % MOD * inv2 % MOD + dH * prevH % MOD)
* (sumW * (sumW + 1) % MOD * inv2 % MOD) % MOD;
ans %= MOD;
}
if (stck.back().first == h[i]) {
stck.back().second += (sumW + w[i]) % MOD;
stck.back().second %= MOD;
} else {
stck.emplace_back(h[i], (sumW + w[i]) % MOD);
}
}
cout << ans << '\n';
}
int main() {
//freopen("input1.txt", "r", stdin);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}
