N,m=map(int,input().split())
s = set()
for i in range(m):
    s.add(int(input()))
memo={0:1}
mod=1000000007
def climb_stairs(n):
    if memo.__contains__(n):
        return memo[n]
    else:
        if s.__contains__(n):
            return 0
        elif n==1:
            return 1
        else:
            memo[n]=((climb_stairs(n-1)%mod + (climb_stairs(n-2) %mod)%mod
            return memo[n]
print(climb_stairs(N))