#include<bits/stdc++.h>
#define endl '\n'
#define fr first
#define sc second
#define ll long long int
const int MAXN = 1e5;
const int MAXL = 20;
const ll MOD = 1e9 + 7;
inline std::pair<int, int> my_min(const std::pair<int, int> &a, const std::pair<int, int> &b){
if(a.fr < b.fr) return a;
if(a.fr > b.fr) return b;
if(a.sc < b.sc) return a;
return b;
}
inline ll mult(ll a, ll b){
return (a * b) % MOD;
}
inline ll fp(ll b, ll p){
if(p == 0) return 1LL;
if(p == 1) return b;
if(p & 1) return mult(b, fp(b, p - 1));
ll aux = fp(b, p / 2);
return mult(aux, aux);
}
inline ll divi(ll a, ll b){
return mult(a, fp(b, MOD - 2));
}
inline ll f(ll n){
n = (n + MOD) % MOD;
return divi(mult(n, n + 1), 2);
}
int lg2[MAXN + 5];
ll N, h[MAXN + 5], w[MAXN + 5], prefw[MAXN + 5];
std::pair<int, int> sparse[MAXN + 5][MAXL + 1];
std::pair<int, int> get(int l, int r){
int j = lg2[r - l + 1];
return my_min(sparse[l][j], sparse[r - (1 << j) + 1][j]);
}
ll rec(int l = 1, int r = N){
if(l > r) return 0;
int minh = get(l, r).fr, id = l;
ll my_ans = 0, other_ans = 0;
my_ans = mult(f(minh), f(prefw[r] - prefw[l - 1]));
while(true){
auto [myh, myid] = get(id, r);
if(myh != minh){
my_ans = (my_ans - mult(f(minh), f(prefw[r] - prefw[id - 1])) + MOD) % MOD;
other_ans += rec(id, r);
break;
}
else{
my_ans = (my_ans - mult(f(minh), f(prefw[myid - 1] - prefw[id - 1])) + MOD) % MOD;
other_ans += rec(id, myid - 1);
id = myid + 1;
}
}
my_ans %= MOD;
other_ans %= MOD;
return (my_ans + other_ans) % MOD;
}
inline void init(){
lg2[1] = 0;
for(int i = 2; i <= MAXN; ++ i){
lg2[i] = lg2[i / 2] + 1;
}
}
int main(){
std::ios_base::sync_with_stdio(false); std::cin.tie(NULL);
init();
std::cin >> N;
for(int i = 1; i <= N; ++ i){
std::cin >> h[i];
sparse[i][0] = {h[i], i};
}
for(int l = 1; l < MAXL; ++ l){
for(int i = 1; i + (1 << l) - 1 <= N; ++ i){
sparse[i][l] = my_min(sparse[i][l - 1], sparse[i + (1 << (l - 1))][l - 1]);
}
}
for(int i = 1; i <= N; ++ i){
std::cin >> w[i];
prefw[i] = prefw[i - 1] + w[i];
}
std::cout << rec() << endl;
}
/**
*/
