#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <set>
#include <stack>
#include <limits.h>
#include <math.h>
#include <iomanip>
#include <bitset>
#include <unordered_map>
#include <unordered_set>
#include <map>
#include <cstring>
#include <sstream>
#pragma GCC target("popcnt")
typedef long long ll;
typedef long double ld;
using namespace std;
const int MOD = 1e9+7;
typedef pair<ld,ld> point;
//#define x first
//#define y second
int n;
ll w[100000],h[100000];
ll wsum[100001];
int hmin[100000][20];
int get_hmin(int l,int r){
int width=r-l;
int p=0;
while((1<<p)<=width)
p++;
p--;
int a=hmin[l][p];
int b=hmin[r-(1<<p)][p];
if(h[a]<h[b])
return a;
else
return b;
}
ll get_combs(ll w,ll h){
ll c1=w*(w+1)/2;
c1%=MOD;
ll c2=h*(h+1)/2;
c2%=MOD;
return(c1*c2)%MOD;
}
ll get(int l,int r,ll level){
if(l==r)
return 0;
int m=get_hmin(l,r);
ll width=(MOD+wsum[r]-wsum[l])%MOD;
ll res=0;
res+=get_combs(width,h[m]);
res+=MOD-get_combs(width,level);
res+=get(l,m,h[m]);
res+=get(m+1,r,h[m]);
return res%MOD;
}
int main(){
ios::sync_with_stdio(false);
cout.tie(NULL);
cin.tie(NULL);
//freopen("speeding.in","r",stdin);
//freopen("speeding.out","w",stdout);
cin>>n;
for(int i=0;i<n;i++)
cin>>h[i];
for(int i=0;i<n;i++)
cin>>w[i];
for(int i=0;i<n;i++)
wsum[i+1]=(wsum[i]+w[i])%MOD;
for(int i=0;i<n;i++)
hmin[i][0]=i;
for(int p=1;p<20;p++){
for(int i=0;i<n;i++){
int a=i;
int b=i+(1<<(p-1));
int c=i+(1<<p);
if(c>n)
break;
if(h[hmin[a][p-1]]<h[hmin[b][p-1]])
hmin[a][p]=hmin[a][p-1];
else
hmin[a][p]=hmin[b][p-1];
}
}
cout<<get(0,n,0)<<"\n";
return 0;
}
