"""
N段の階段 M個の階段が壊れている
"""

N, M = map(int, input().split())
arr = [int(input()) for _ in range(M)]
no_step =[0]*N

for i in range(M):
    no_step[arr[i]-1]=1

count = [0]*N
if no_step[0]==0:
    count[0]=1

if no_step[1]==1:
    count[1]=0
elif no_step[0]==0 and no_step[1]==0:
    count[1]=2
elif no_step[0]==1 and no_step[1]==0:
    count[1]=1

for i in range(3,N+1,1):
    count[i-1] = count[i-2]+count[i-3]
    if no_step[i-1] == 1:
        count[i-1] = 0

ans =count[N-1]%1000000007
print(ans)