#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#define black_tree tree<ll,null_type,less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update>
#define pair_black_tree tree<pair<ll,ll>,null_type,less<pair<ll,ll> >,rb_tree_tag,tree_order_statistics_node_update>
#define gp __gnu_pbds
#define INF 1000000000
#define MOD 1000000007
#define MAX 100001
#define endl '\n'
#define ll long long
#define ld long double
#define lli long long int
#define ull unsigned long long
#define ulli unsigned long long int
#define pb push_back
#define pf push_front
#define ook order_of_key
#define fbo find_by_order
#define np next_permutation
#define mp make_pair
#define eb emplace_back
#define mae max_element
#define mie min_element
#define lb lower_bound
#define ub upper_bound
#define bs binary_search
#define ff first
#define ss second
using namespace std;
using namespace gp;
vector<pair<ll,ll> >v;
vector<ll>h(MAX),w(MAX);
ll n,a,b,c,ans,k=500000004;
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n;
for(int i=0;i<n;i++){
cin>>h[i];
}
for(int i=0;i<n;i++){
cin>>w[i];
}
v.pb({0,0});
for(int i=0;i<=n;i++){
c=0;
while(v.back().ff>h[i]){
a=max(h[i],v[v.size()-2].ff);
b=v.back().ff-a;
c=(c+v.back().ss)%MOD;
v.pop_back();
ans+=(((b*(b+1)%MOD)*k)%MOD+(a*b)%MOD)*(((c*(c+1)%MOD)*k)%MOD)%MOD;
ans%=MOD;
}
if(v.back().ff==h[i]){
v.back().ss=(v.back().ss+c+w[i])%MOD;
}
else{
v.pb({h[i],(c+w[i])%MOD});
}
}
cout<<ans;
}
