#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int N = 1e5+10;
const int MOD = 1e9+7;
ll h[N], w[N], pw[N], dp[N], n;
void solve() {
cin>>n;
for (int i=1; i<=n; ++i) cin>>h[i];
for (int i=1; i<=n; ++i) cin>>w[i];
for (int i=1; i<=n; ++i) pw[i]=pw[i-1]+w[i], pw[i]%=MOD;
dp[0]=0, h[0]=0;
ll ans=0; // dp[i] -> from {1, 2, ..., i} ends on rightmost point of i
stack<int> st; st.push(0);
for (int i=1; i<=n; ++i) {
while (h[st.top()] > h[i]) st.pop();
ll hl=(h[i]*(h[i]+1)/2)%MOD;
// add all rects which start before (st.top())
(ans+=dp[st.top()]*w[i])%=MOD;
// add all rects which contains atleast one from w[i] and suffix of others
(ans+=(w[i]*(pw[i-1]-pw[st.top()]+1)%MOD)*hl)%=MOD;
(ans+=((w[i]*(w[i]-1)/2)%MOD)*hl)%=MOD;
(dp[i]+=dp[st.top()]+(pw[i]-pw[st.top()])*hl)%=MOD;
st.push(i);
}
/*
cout<<"dp: ";
for (int i=1; i<=n; ++i) cout<<dp[i]<<" ";
cout<<"\n"; */
ans%=MOD;
(ans+=MOD)%=MOD;
assert(ans >= 0 && ans < MOD);
cout<<ans<<"\n";
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
int t=1; //cin>>t;
while (t--) solve();
}
