#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
using namespace std;
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const int MAXN = 1e5+10;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const ll MOD = 1e9+7;
const ll inv2 = 500000004;
ll gauss(ll a){ return (((a*(a+1))%MOD)*inv2)%MOD; }
void solve(){
int n; cin >> n;
vector<pair<ll, pll>> arr(n);
ll id=0;
for(int i=0;i<n;i++)
cin >> arr[i].fi;
for(int i=0;i<n;i++){
arr[i].se.fi=id;
ll x; cin >> x;
id+=x;
arr[i].se.se=id;
}
set<pair<pll, ll>> st;
st.insert({{0, arr[n-1].se.se}, 0});
sort(all(arr));
ll ans=0;
for(int i=0;i<n;i++){
auto aux=st.upper_bound({{arr[i].se.fi+1, -1}, -1});
aux--;
pair<pll, ll> curr=*aux;
st.erase(aux);
ans+=(((gauss((arr[i].fi)%MOD)-gauss((curr.se)%MOD)+MOD)%MOD)*gauss((curr.fi.se-curr.fi.fi)%MOD))%MOD;
ans%=MOD;
if(arr[i].se.fi!=curr.fi.fi)
st.insert({{curr.fi.fi, arr[i].se.fi}, arr[i].fi});
if(arr[i].se.se!=curr.fi.se)
st.insert({{arr[i].se.se, curr.fi.se}, arr[i].fi});
}
cout << ans << "\n";
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL);
// freopen("fetiera.in", "r", stdin);
int tt=1;
// cin >> tt;
while(tt--)
solve();
return 0;
}
