// Only GOD
// believe in yourself
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
#define F first
#define S second
#define pb push_back
#define all(x) x.begin(), x.end()
#define bit(x, y) ((x >> y)&1)
#define sz(x) (int)x.size()
#define kill(x) return cout << x << '\n', void()
#define KILL(x) return cout << x << '\n', 0
#define int ll
const int N = 2e5+10;
const int INF = 1e9;
const int MOD = 1e9+7;
int mul(int a, int b){
a %= MOD;
b %= MOD;
return (a*b)%MOD;
}
int add(int a, int b){
return (a+b+MOD)%MOD;
}
int dp[N], h[N], w[N];
int inv;
int f(int n){
return mul(mul(n, n+1)%MOD, inv)%MOD;
}
int pw(int a, int b){
int res = 1;
while(b){
if(b & 1)
res = mul(a, res);
a = mul(a, a);
b >>= 1;
}
return res;
}
int32_t main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int n;
cin >> n;
inv = pw(2, MOD-2);
for(int i = 1; i <= n; i++){
cin >> h[i];
}
for(int i = 1; i <= n;i++)
cin >> w[i];
int ans = 0;
if(n <= 1000){
for(int i = 1; i <= n; i++){
int mn = h[i];
dp[i] = mul(w[i], f(h[i]));
dp[i] = add(dp[i], mul(f(w[i]-1), f(h[i])));
for(int j = i-1; j >= 1; j--){
mn = min(mn, h[j]);
dp[i] = add(dp[i], mul(w[j],mul(w[i], f(mn))));
}
ans = add(ans, dp[i]);
}
KILL(ans);
}
else if(*max_element(h+1, h+1+n) <= 2){
int sum = 0;
for(int i = 1; i <= n; i++){
sum += w[i];
if(h[i]==2){
if(h[i-1] == 2){
dp[i] = mul(dp[i-1], w[i]);
}
else{
dp[i] = sum+2;
}
dp[i] = add(dp[i], mul(2, f(w[i])));
}
else{
dp[i] = sum;
}
ans = add(ans, dp[i]);
}
KILL(ans);
}
else if(is_sorted(h+1, h+n+1)){
for(int i = 1; i <= n; i++){
dp[i] = mul(w[i], f(h[i]));
dp[i] = add(dp[i], mul(f(w[i]-1), f(h[i])));
dp[i] = add(mul(dp[i-1], w[i]), dp[i]);
ans = add(ans, dp[i]);
}
KILL(ans);
}
}
