package contest180608;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.InputMismatchException;

// ためし
public class D2 {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		int n = ni(), m = ni();
		int[] xs = na(m);
		// 17×9920467×592951213
		long[] divs = {17, 9920467, 592951213};
		long[] mods = new long[3];
		dp = new int[n];
		for(int i = 0;i < 3;i++){
			mods[i] = go((int)divs[i], xs, n);
		}
		out.println(crtx(divs, mods));
	}
		
	int[] dp;
	
	long go(int mod, int[] xs, int n)
	{
		Arrays.fill(dp, 0);
		dp[0] = 1;
		for(int i = 1;i < n;i++){
			for(int x : xs){
				if(i-x >= 0){
					dp[i] += dp[i-x];
					if(dp[i] >= mod)dp[i] -= mod;
				}
			}
		}
		return dp[n-1];
	}
	
	
	public static BigInteger b(long x){ return BigInteger.valueOf(x); }
	
	public static BigInteger[] exGCD(BigInteger a, BigInteger b)
	{
		BigInteger p = BigInteger.ONE, q = BigInteger.ZERO, r = BigInteger.ZERO, s = BigInteger.ONE;
		while(b.signum() > 0){
			BigInteger c = a.divide(b);
			BigInteger d;
			d = a; a = b; b = d.mod(b);
			d = p; p = q; q = d.subtract(c.multiply(q));
			d = r; r = s; s = d.subtract(c.multiply(s));
		}
		return new BigInteger[]{a, p, r};
	}
	
	
	public static BigInteger crtx(long[] divs, long[] mods)
	{
		BigInteger div = b(divs[0]), mod = b(mods[0]);
		for(int i = 1;i < divs.length;i++){
			BigInteger[] apr = exGCD(div, b(divs[i]));
			BigInteger mm = b(mods[i]).subtract(mod);
			if(mm.mod(apr[0]).signum() != 0)return b(-1);
			BigInteger da = div.divide(apr[0]);
			BigInteger ndiv = b(divs[i]).multiply(da);
			BigInteger nmod = apr[1].multiply(mm).multiply(da).add(mod).mod(ndiv);
			if(nmod.signum() < 0)nmod = nmod.add(ndiv);
			div = ndiv;
			mod = nmod;
		}
		return mod;
	}

	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//		Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//			@Override
//			public void run() {
//				long s = System.currentTimeMillis();
//				solve();
//				out.flush();
//				if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//			}
//		};
//		t.start();
//		t.join();
	}
	
	public static void main(String[] args) throws Exception { new D2().run(); }
	
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private long[] nal(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
	
	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[][] nmi(int n, int m) {
		int[][] map = new int[n][];
		for(int i = 0;i < n;i++)map[i] = na(m);
		return map;
	}
	
	private int ni() { return (int)nl(); }
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}