#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
const int MOD = 1e9 + 7;
const int sz = 1e5 + 5;
long long INV;
long long h[sz], w[sz];
long long s[sz], f[sz];
long long bp(long long a, long long b){
long long ans = 1;
while(b){
if(b & 1){
ans = (ans * a) % MOD;
}
a = (a % MOD) * (a % MOD) % MOD;
b >>= 1;
}
return ans;
}
long long c2(long long x){
return (x * (x+1) % MOD) * (INV % MOD) % MOD;
}
long long add(long long a, long long b){
return ((a % MOD) + (b % MOD)) % MOD;
}
long long mul(long long a, long long b){
return (a % MOD) * (b % MOD) % MOD;
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
//freopen("main.inp","r",stdin);
//freopen("main.out","w",stdout);
int n;
cin>>n;
for(int i=1;i<=n;++i){
cin>>h[i];
}
for(int i=1;i<=n;++i){
cin>>w[i];
s[i] = (s[i-1] + w[i]) % MOD;
}
INV = bp(2, MOD-2);
stack<int> st; //ascending stack
st.push(0);
long long ans = 0;
for(int i=1;i<=n;++i){
while(st.size() && h[st.top()] >= h[i]){ //h[st.top()] < h[i]
st.pop();
}
long long len = (s[i] - s[st.top()] + MOD) % MOD;
long long l1 = (len - w[i] + MOD) % MOD;
long long A = 0; //equal heights.
long long B = 0; //smaller heights.
//# of sub-rect in current section.
A += mul(c2(h[i]), c2(w[i]));
//# of sub-rect of section with height >= h[i] appended to current section.
A += mul(mul(w[i], l1), c2(h[i]));
A %= MOD;
B += mul(f[st.top()], w[i]);
B %= MOD;
f[i] = add(f[st.top()], mul(len, c2(h[i])));
st.push(i);
ans = (ans + A + B) % MOD;
}
cout<<ans;
return 0;
}
