#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 1e5 + 10;
const int MOD = 1e9 + 7;
int h[MAXN], w[MAXN], s[MAXN];
int dp[MAXN];
int32_t main(){
cin.tie(0)->sync_with_stdio(0);
int n; cin >> n;
for(int i=1; i<=n; i++){
cin >> h[i];
}
for(int i=1; i<=n; i++){
cin >> w[i];
s[i] = s[i - 1] + w[i];
}
stack<int> q;
int ans = 0;
for(int i=1; i<=n; i++){
while(!q.empty() && h[q.top()] > h[i]) q.pop();
int j = 0;
if(!q.empty()) j = q.top();
int l = (s[i - 1] - s[j]) % MOD;
int aux = (dp[j] + ((((h[i] * (h[i] + 1)) / 2) % MOD) * l) % MOD) % MOD;
int cnt = ((((h[i] * (h[i] + 1)) / 2) % MOD) * ((w[i] * (w[i] - 1)) / 2) % MOD) % MOD;
dp[i] = (aux + ((((h[i] * (h[i] + 1)) / 2) % MOD) * w[i]) % MOD) % MOD; // termina no i
ans = (ans + dp[i] + (aux * (w[i] - 1)) % MOD + cnt) % MOD;
q.push(i);
}
cout << ans << "\n";
return 0;
}
