import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;

public class Main {
	static long mod=(long)(1e9+7);
	static long mod1=99991;
	static ArrayList<Integer> al[];
	static boolean vis[];
	static HashMap<String,Long> hm;
	static long bit[],n1,dp[][],ans[];
	static int root;
	public static void main(String args[]) throws IOException{
		new Thread(null,new Runnable(){
			public void run(){
				new Main().run();
			}
		},"1",1<<23).start();

	}

	protected void run() {
		// TODO Auto-generated method stub
		InputReader in 		= new InputReader(System.in);
		OutputWriter out	=	new OutputWriter(System.out);
		int n=in.readInt();
		int a[]=new int[n];
		long dp[]=new long[n];
		dp[0]=1;
		for(int i=0;i<n;i++){
			a[i]=in.readInt();
			if(i>0)
				dp[i]=2*dp[i-1];
			dp[i]%=mod;
		}
		out.printLine(dp[n-1]);
		out.flush();
		out.close();
	}



	private long gcd(long i, long j) {
		if(i%j==0)
			return j;
		if(j%i==0)
			return i;
		long max=Math.max(i, j);
		long min=Math.min(i,j);
		return gcd(max%min,min);
	}

	private long inv(long l) {
		// TODO Auto-generated method stub
		return pow(l,mod-2,mod);
	}

	public static long pow(long n,long p,long m)
	{
		long  result = 1;
		if(p==0)
			return 1;
		if (p==1)
			return n;
		while(p!=0)
		{
			if(p%2==1)
				result *= n;
			if(result>=m)
				result%=m;
			p >>=1;
		n*=n;
		if(n>=m)
			n%=m;
		}
		return result;
	}

}

class point {
	int x,y;
	point(int x,int y){
		this.x=x;
		this.y=y;
	}


}

class node implements Comparable<node>{
	public node(int i, int j,String s) {
		x=i;
		depth=j;
		str=s;
	}

	int x;int depth;
	String str;
	@Override
	public int compareTo(node o) {
		return Integer.compare(o.depth, depth);
	}

	public int hashCode(){
		return (int)x*31+depth*17;
	}
	public boolean equals(Object o){
		node od=(node)o;
		return depth==od.depth && od.x==x;
	}
}


class InputReader {

	private InputStream stream;
	private byte[] buf = new byte[1024];
	private int curChar;
	private int numChars;
	private SpaceCharFilter filter;

	public InputReader(InputStream stream) {
		this.stream = stream;
	}

	public int read() {
		if (numChars == -1)
			throw new InputMismatchException();
		if (curChar >= numChars) {
			curChar = 0;
			try {
				numChars = stream.read(buf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (numChars <= 0)
				return -1;
		}
		return buf[curChar++];
	}

	public int readInt() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		int res = 0;
		do {
			if (c < '0' || c > '9')
				throw new InputMismatchException();
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public String readString() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		StringBuilder res = new StringBuilder();
		do {
			res.appendCodePoint(c);
			c = read();
		} while (!isSpaceChar(c));
		return res.toString();
	}

	public boolean isSpaceChar(int c) {
		if (filter != null)
			return filter.isSpaceChar(c);
		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	public String next() {
		return readString();
	}

	public interface SpaceCharFilter {
		public boolean isSpaceChar(int ch);
	}
}

class OutputWriter {
	private final PrintWriter writer;

	public OutputWriter(OutputStream outputStream) {
		writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
	}

	public OutputWriter(Writer writer) {
		this.writer = new PrintWriter(writer);
	}

	public void print(Object...objects) {
		for (int i = 0; i < objects.length; i++) {
			if (i != 0)
				writer.print(' ');
			writer.print(objects[i]);
		}
	}

	public void printLine(Object...objects) {
		print(objects);
		writer.println();
	}

	public void close() {
		writer.close();
	}

	public void flush() {
		writer.flush();
	}

}

class IOUtils {

	public static int[] readIntArray(InputReader in, int size) {
		int[] array = new int[size];
		for (int i = 0; i < size; i++)
			array[i] = in.readInt();
		return array;
	}

}