c_mod=1000000007
n,m = map(int,input().split())

step=[0]*n
for _ in range(m):
    a=int(input())
    step[a-1]=-1

if step[0]!=-1:
    step[0]=1
if step[1]!=-1:
    step[1]=1
for i in range(n):
    if step[i]==-1:
        continue
    if step[i-1]!=-1:
        step[i]+=step[i-1]
    if step[i-2]!=-1:
        step[i]+=step[i-2]
print(step[n-1]%c_mod)
