import sys
sys.setrecursionlimit(10**9)
def input():
    return sys.stdin.readline().rstrip()

def main():
    N,M=map(int,input().split())
    a=[int(input()) for i in range(M)]
    dp=[1]*(N+1)
    if M!=0:
        dp[1]=0 if a[0]==1 else 1
        for i in a:
            dp[i]=0
        for i in range(1,N):
            if dp[i+1]!=0:
                dp[i+1] = (dp[i]+dp[i-1]) % 1000000007
    print(dp[N])


if __name__ == '__main__':
    main()
