Problem:
Score : 400 points

Problem Statement

Mountaineers Mr. Takahashi and Mr. Aoki recently trekked across a certain famous mountain range.
The mountain range consists of N mountains, extending from west to east in a straight line as Mt. 1, Mt. 2, ..., Mt. N.
Mr. Takahashi traversed the range from the west and Mr. Aoki from the east.

The height of Mt. i is h_i, but they have forgotten the value of each h_i.
Instead, for each i (1 ≤ i ≤ N), they recorded the maximum height of the mountains climbed up to the time they reached the peak of Mt. i (including Mt. i).
Mr. Takahashi's record is T_i and Mr. Aoki's record is A_i.

We know that the height of each mountain h_i is a positive integer.
Compute the number of the possible sequences of the mountains' heights, modulo 10^9 + 7.

Note that the records may be incorrect and thus there may be no possible sequence of the mountains' heights.
In such a case, output 0.

Constraints

1 ≤ N ≤ 10^5

1 ≤ T_i ≤ 10^9

1 ≤ A_i ≤ 10^9

T_i ≤ T_{i+1} (1 ≤ i ≤ N - 1)

A_i ≥ A_{i+1} (1 ≤ i ≤ N - 1)

Input

The input is given from Standard Input in the following format:

N
T_1 T_2 ... T_N
A_1 A_2 ... A_N

Output

Print the number of possible sequences of the mountains' heights, modulo 10^9 + 7.

Sample Input 1

5
1 3 3 3 3
3 3 2 2 2

Sample Output 1

4

The possible sequences of the mountains' heights are:

1, 3, 2, 2, 2

1, 3, 2, 1, 2

1, 3, 1, 2, 2

1, 3, 1, 1, 2

for a total of four sequences.

Sample Input 2

5
1 1 1 2 2
3 2 1 1 1

Sample Output 2

0

The records are contradictory, since Mr. Takahashi recorded 2 as the highest peak after climbing all the mountains but Mr. Aoki recorded 3.

Sample Input 3

10
1 3776 3776 8848 8848 8848 8848 8848 8848 8848
8848 8848 8848 8848 8848 8848 8848 8848 3776 5

Sample Output 3

884111967

Don't forget to compute the number modulo 10^9 + 7.

Sample Input 4

1
17
17

Sample Output 4

1

Some mountain ranges consist of only one mountain.

Solution in Java7 (OpenJDK 1.7.0) (judge verdict: Wrong Answer)

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        final int BASE = 1000000007;
        int n = sc.nextInt();
        int taka[] = new int [n];
        int ao[] = new int [n];

        for(int i=0;i<n;i++){
            taka[i]= sc.nextInt();
        }
        for(int i=0;i<n;i++){
            ao[i]= sc.nextInt();
        }

        long pattern = 1;
        boolean flag = true;

//        if(taka[n-1]!=ao[0]){
//            flag = false;
//        }

        for(int i=0;i<n&&flag;i++){
            int max_t=0,min_t=0;
            int max_a=0,min_a=0;

            if(i==0){
                max_t = taka[0];
                min_t = taka[0];
            }
            else{
                if(taka[i]==taka[i-1]){
                    max_t = taka[i];
                    min_t = 1;
                }
                else {
                    max_t = taka[i];
                    min_t = taka[i];
                }
            }

            if(i==n-1){
                max_a = ao[n-1];
                min_a = ao[n-1];
            }
            else{
                if(ao[i+1]==ao[i]){
                    min_a =1;
                    max_a = ao[i];
                }
                else {
                    max_a = ao[i];
                    min_a = ao[i];
                }
            }

            if(max_t<min_a || max_a<min_t){
                flag = false;
            }
            else{
                int tmp = Math.min(max_a,max_t) - Math.max(min_a,min_t)+1;
                pattern *= tmp;
                while (pattern>=BASE) {
                    pattern = pattern % BASE;
                }
            }

        }

        //if(!flag) pattern = 0;

        System.out.println(pattern);


    }

 }