#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MOD = 1e9+7, INV = 250000002;
int f(int n, int m) {
return n * m % MOD * (n + 1) % MOD * (m + 1) % MOD * INV % MOD;
}
signed main() {
//input and sum
int n;
cin >> n;
vector<int> h(n), w(n), suffixWSum(n);
for(int i = 0; i < n; i++) cin >> h[i];
for(int i = 0; i < n; i++) cin >> w[i];
for(int i = n-1; i > -1; i--) suffixWSum[i] = w[i] + (i == n-1 ? 0 : suffixWSum[i+1]);
//linearily go over and compute result
int res = 0, m = suffixWSum[0], pastH = 0;
for(int i = 0; i < n; i++) {
if(i != 0 && h[i-1] < h[i]) {
res = (res + f(h[i-1], m) - f(pastH, m)) % MOD;
//cout << h[i-1] << " " << m << "\n";
m = suffixWSum[i], pastH = h[i-1];
}
}
//cout << h[n-1] << " " << m << "\n";
res = (res + f(h[n-1], m) - f(pastH, m)) % MOD;
cout << res << "\n";
}
