n,m=map(int,input().split())
danger=[int(input()) for i in range(m)]
steps=[0]*(n+1)
steps[0]=1

if 1 in danger:
    steps[1]=0
else:
    steps[1]=1

for this_step in range(2,n+1):
    if this_step in danger:
        ap=0
    else:
        steps[this_step]=steps[this_step-1]+steps[this_step-2]

print(steps[-1]%1000000007)