import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = Integer.parseInt(sc.next());
    int m = Integer.parseInt(sc.next());
    int brokenStair;
    int[] stair = new int[n+1];
    Arrays.fill(stair, -1);
    stair[n-1] = 1;
    stair[n-2] = 1;
    for(int i = 0; i < m; i++) {
      brokenStair = Integer.parseInt(sc.next());
      stair[brokenStair-1] = 0;
    }
    for(int i = n-3; i >= 0; i--) {
      if(stair[i] == 0) continue;
      stair[i] = (stair[i+1] + stair[i+2]) % 1000000007;
    }
    int answer = stair[0] + stair[1];
    System.out.println(answer);
  }
}
