n,m=map(int,input().split())
l=[0]*m
for i in range(m):
    l[i]=int(input())
#print(l)
dp=[0]*(n+1)
dp[0]=1
for j in range(1,n+1):
    if j not in l:
        dp[j]=-1
#print(dp)
if dp[1]==-1:dp[1]=1
for i in range(2,n+1):
    if dp[i]==-1:
        dp[i]=(dp[i-1]+dp[i-2])%1000000007
print(dp[-1]%1000000007)