import sys
input=sys.stdin.readline

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

dp = [0]*(n+1)
dp[0] = 1
dp[1] = 0 if 1 in a else 1
for i in range(2,n+1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = dp[i-1] + dp[i-2]

print(dp[n]%(10**9+7))
