n,m=list(map(int,input().split()))
a=[int(input()) for i in range(m)]

for i in range(m-1):
  if a[i]+1==a[i+1]:
    print(0)
    exit()
    
n1,n2=1,0
for j in range(1,n):
  if j in a:
    break
  else:
    if j-1 in a:
        n2=n1
    else:
        tmp=n1
        n1=n1+n2
        n2=tmp
ans=n1%1000000007
print(ans)