2
1 31
 2
1 0
 10
450661 128600 993228 725823 293549 33490 843121 903634 556169 448234
 1
1
 5
1 3 5 7 9
 6
524 529 5249 524 529 529
 3
1 2 3
 2
0 1
 55
0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 3 4 5 6 7 8 9 4 5 6 7 8 9 5 6 7 8 9 6 7 8 9 7 8 9 8 9 9
 16
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
 3
128 1024 2048
 10
3 3 3 5 5 3 3 3 3 5
 1
0
 2
1 2
 2
0 0
 2
1 1

0
 2
 632
 0
 0
 24
 2
 2
 621247139
 64594
 4
 0
 1
 1
 3
 0


import java.util.Scanner;


public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		try{
		Scanner sc = new Scanner(System.in);
		String input1 = sc.nextLine();
		String input2 = sc.nextLine();
		
		int n = Integer.parseInt(input1);
		
		String str1[] = input2.split(" ");
		int numbers[] = new int[n];
		int zeroCount = 0;
		int nonZeroCount = 0;
		for(int i=0; i<str1.length; i++){
			numbers[i] = Integer.parseInt(str1[i].trim());
			if(numbers[i]==0){
				zeroCount++;
			}else{
				nonZeroCount++;
			}
		}
		//System.out.println("zeroCount:" + zeroCount);
		//System.out.println("nonZeroCount:" + nonZeroCount);
		
		if(zeroCount==0){
			System.out.println(0);
		}else if(zeroCount==1){
			System.out.println((int)(Math.pow(2, nonZeroCount)) % 1000000007);;
		}else if (zeroCount > 1){
			System.out.println((int)(Math.pow(2,nonZeroCount) - 1 + zeroCount)%1000000007);
		}
		
		}
		catch(Exception e){
			//e.printStackTrace();
		}
	}

}
