#include <bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define st first
#define nd second
#define pii pair<int,int>
#define piii pair<int,pii>
#define sp " "
#define nl "\n"
#define all(x) x.begin(),x.end()
#define fastio() ios_base::sync_with_stdio(0);cin.tie(0);
#define ll long long
#define int ll
using namespace std;
const int N = 100005;
const int INF = 1e9+7;
const int mod = 1e9+7;
const int inv2 = 500000004;
int n,w[N],h[N],ans;
int comb2(int x){
return x*(x-1)%mod*inv2%mod;
}
int32_t main(){
fastio()
cin >> n;
for(int i=0;i<n;i++)
cin >> h[i];
for(int i=0;i<n;i++)
cin >> w[i];
vector<pii> vec;
vec.pb({0,0});
for(int i=0;i<=n;i++){
int len=0;
while(vec.back().st>h[i]){
int prv=max(h[i],vec[(int)vec.size()-2].st);
int dif=vec.back().st-prv;
len=(len+vec.back().nd)%mod;
vec.pop_back();
ans+=((comb2(dif+1)+(dif*prv)%mod))*comb2(len+1);
ans%=mod;
}
if(vec.back().st==h[i]){
vec.back().nd=(vec.back().nd+len+w[i])%mod;
}
else{
vec.pb({h[i],(len+w[i])%mod});
}
}
cout << ans << nl;
}
