import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.BitSet;
import java.util.NoSuchElementException;

public class Main {
  private static class Task {
    void solve(FastScanner in, PrintWriter out) {
      int M = in.nextInt();
      int N = in.nextInt();
      int[] c = in.nextIntArray(N);
      Arrays.sort(c);

      int[] dp = new int[M + 1];
      Arrays.fill(dp, -1);
      dp[0] = 0;
      for (int cup : c) {
        for (int m = 0; m + cup <= M; m++) if (dp[m] >= 0) dp[m + cup] = Math.max(dp[m + cup], dp[m] + 1);
      }

      int[] primes = sieveEratos(M + 1);
      boolean[] used = new boolean[M + 1];
      int ans = 0;
      for (int prime : primes) {
        if (M - prime < 0) break;
        if (dp[M - prime] < 0) continue;
        ans += dp[M - prime];
        used[M - prime] = true;
      }

      int max = 0;
      for (int i = 0; i <= M; i++) {
        if (!used[i]) max = Math.max(max, dp[i]);
      }
      out.println(ans + max);

    }

    static int[] sieveEratos(int n) {
      BitSet primeset = new BitSet();
      primeset.flip(2, n + 1);
      for (int q = primeset.nextSetBit(2); q != -1 && q * q <= n; q = primeset.nextSetBit(q + 1)) {
        for (int i = q * q; i <= n; i += q) {
          primeset.clear(i);
        }
      }

      int[] primes = new int[primeset.cardinality()];
      int p = 0;
      for (int q = primeset.nextSetBit(2); q != -1; q = primeset.nextSetBit(q + 1)) {
        primes[p++] = q;
      }
      return primes;
    }

  }

  // Template
  public static void main(String[] args) {
    OutputStream outputStream = System.out;
    FastScanner in = new FastScanner();
    PrintWriter out = new PrintWriter(outputStream);
    Task solver = new Task();
    solver.solve(in, out);
    out.close();
  }
  private static class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int bufferLength = 0;

    private boolean hasNextByte() {
      if (ptr < bufferLength) {
        return true;
      } else {
        ptr = 0;
        try {
          bufferLength = in.read(buffer);
        } catch (IOException e) {
          e.printStackTrace();
        }
        if (bufferLength <= 0) {
          return false;
        }
      }
      return true;
    }

    private int readByte() {
      if (hasNextByte()) return buffer[ptr++];
      else return -1;
    }

    private static boolean isPrintableChar(int c) {
      return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    }

    boolean hasNext() {
      skipUnprintable();
      return hasNextByte();
    }

    public String next() {
      if (!hasNext()) throw new NoSuchElementException();
      StringBuilder sb = new StringBuilder();
      int b = readByte();
      while (isPrintableChar(b)) {
        sb.appendCodePoint(b);
        b = readByte();
      }
      return sb.toString();
    }

    long nextLong() {
      if (!hasNext()) throw new NoSuchElementException();
      long n = 0;
      boolean minus = false;
      int b = readByte();
      if (b == '-') {
        minus = true;
        b = readByte();
      }
      if (b < '0' || '9' < b) {
        throw new NumberFormatException();
      }
      while (true) {
        if ('0' <= b && b <= '9') {
          n *= 10;
          n += b - '0';
        } else if (b == -1 || !isPrintableChar(b)) {
          return minus ? -n : n;
        } else {
          throw new NumberFormatException();
        }
        b = readByte();
      }
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    double[] nextDoubleArray(int n) {
      double[] array = new double[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextDouble();
      }
      return array;
    }

    double[][] nextDoubleMap(int n, int m) {
      double[][] map = new double[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextDoubleArray(m);
      }
      return map;
    }

    public int nextInt() {
      return (int) nextLong();
    }

    public int[] nextIntArray(int n) {
      int[] array = new int[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextInt();
      }
      return array;
    }
  }
}