
mod=10**9+7
n, m = map(int, input().split())
ai=[]

for i in range(m):
    ai.append(int(input()))
#print(ai)

dp=[]
for i in range(n+1):
    dp.append(0)

dp[0]=1
if 1 in ai:
    dp[1]=0
else:
    dp[1]=1

for i in range(2,n+1):
    if i in ai:
        continue
    dp[i]=(dp[i-1]+dp[i-2])%mod

#print(dp)
print(dp[n])
