#include "bits/stdc++.h"
#define int long long
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
using namespace std;
const long long INF = 1ll << 60;
const int N = 1e5 + 5;
const int M = 1e9 + 7;
int pw(int a) {
a %= M;
return a * (a - 1) / 2 % M;
}
int H[N], W[N], n, ps[N], lt[N], rt[N];
signed main() {
ios::sync_with_stdio(0), cin.tie(0);
cin >> n;
FOR(i, 1, n + 1) cin >> H[i];
FOR(i, 1, n + 1) cin >> W[i];
vector<int> st{0};
H[0] = H[n + 1] = -INF;
FOR(i, 1, n + 1) {
while (H[i] < H[st.back()]) st.pop_back();
lt[i] = st.back();
st.push_back(i);
}
st = {n + 1};
for (int i = n; i >= 1; i--) {
while (H[i] <= H[st.back()]) st.pop_back();
rt[i] = st.back();
st.push_back(i);
}
FOR(i, 1, n + 1) ps[i] = ps[i - 1] + W[i];
int ans = 0;
FOR(i, 1, n + 1) {
int L = ps[i - 1] - ps[lt[i]] + 1;
int R = ps[rt[i] - 1] - ps[i] + 1;
int re = pw(L + R + W[i] - 1) - pw(L) - pw(R);
ans += re % M * pw(H[i] + 1) % M;
}
ans %= M;
if (ans < 0) ans += M;
cout << ans << '\n';
return 0;
}
