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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;




	class contest
	{
				
		
		static void Main(string[] args)
		{

		  
            var n = int.Parse(Console.ReadLine());
            var L = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();            
            var R = Console.ReadLine().Split(' ').Select(int.Parse).ToList();

            var arr = new int[n];
            var arL = new int[n];
            var arR = new int[n];
            var check = new bool[n];

            //long test = (long)Math.Pow(8847,4);
            //Console.WriteLine(test);
            


            int mxL = 0;
            int mxR = 0;
            for(int i = 0; i < n; i++)
            {
                if (L[i] > mxL)
                {
                    arr[i] = L[i];
                    arL[i] = L[i];
                    mxL = L[i];
                    check[i] = true;
                }
                //else if (L[i] == mxL) arL[i] = mxL;

                if (R[n - 1 - i] > mxR)
                {
                    arr[n - 1 - i] = R[n - i - 1];
                    arR[n - 1 - i] = R[n - 1 - i];
                    mxR = R[n - i - 1];
                    check[n-1-i] = true;
                }
                //else if (R[n - 1 - i] == mxR) arR[n-1-i] = mxR;
            }

            bool ok = true;
            for(int i=0; i< n; i++)
            {
                if(arL[i]>0 && arR[i]>0)
                {
                    if(arL[i] != arR[i])
                    {
                        ok = false;
                        break;
                    }
                }
            }


            if (!ok) Console.WriteLine(0);
            else if (n == 1)
            {
                if (L[0] == R[0]) Console.WriteLine(1);
                else Console.WriteLine(0);
            }
            else if (arr.Count(c => c == 0) == 0) Console.WriteLine(1);
            else
            {
                long count = 1;
                //long range = 0;


                long tmp = 0;

                var memo = new int[2];









                memo = new int[2];
                for (int i = 0; i < n - 1; i++)
                {
                    if (arr[i + 1] == 0)
                    {
                        if (memo[0] == 0) memo[0] = arr[i];
                        tmp++;
                    }
                    else if (tmp > 0)
                    {
                        memo[1] = arr[i + 1];
                        
                        count *= (long)Math.Pow(Math.Max(memo[0], memo[1]) - 1, tmp);
                        tmp = 0;
                        memo = new int[2];
                    }
                }




                long mod = 1000000007;
                count %= mod;



                Console.WriteLine(count);
            }
 
           



		
        }
		
		
			
	}