import sys,math
N,M = map(int,input().split())
a = [int(input()) for i in range(M)]
dp = [0] * (N+1)
mod = 10**9+7
for i in range(N,-1,-1):
    if i in a:
        continue
    elif i == N or i == N-1:
        dp[i] = 1
    else:
        dp[i] = dp[i+1] + dp[i+2]
print(dp[0]%mod)
