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)
    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]
    print(dp[N]%1000000007)


if __name__ == '__main__':
    main()