#include <bits/stdc++.h>
#define ll long long
#define fr first
#define sc second
#define ps push
#define pp pop
#define psb push_back
#define ppb pop_back
#define ft front
using namespace std;
const ll mod = 1e9 + 7;
ll expo(ll a, ll b){
if(b == 1) return a;
else if(b == 0) return 1;
else{
ll x = expo(a, b / 2); x *= x; x %= mod;
if(b & 1) return (x * a) % mod;
else return x;
}
}
ll seq(ll a){
return (((a * (a + 1)) % mod) * expo(2, mod - 2)) % mod;
}
ll comb_grid(ll a, ll b){
return (a * b) % mod;
}
int main(){
int n; cin >> n;
ll h[n]; for(int i = 0; i < n; i++) cin >> h[i];
ll w[n]; for(int i = 0; i < n; i++) cin >> w[i];
ll ans = 0; stack <pair <ll, ll>> st;
for(int i = 0; i < n; i++){
ll tot = w[i];
// cout << i << ' ' << !st.empty() << ' ';
while(!st.empty() && st.top().fr >= h[i]){
tot += st.top().sc, tot %= mod;
st.pop();
}
// cout << "> " << ans << '\n';
ans += comb_grid(seq(h[i]), seq(tot)), ans %= mod;
st.push({h[i], tot});
}
ll h_min = st.top().fr, w_tot = st.top().sc;
st.pop();
while(!st.empty()){
h_min = st.top().fr;
ans += comb_grid((h_min * st.top().sc) % mod, (h_min * w_tot) % mod), ans %= mod;
w_tot += st.top().sc;
st.pop();
}
cout << ans << endl;
}
