import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 7)

MOD = 10 ** 9 + 7
n,m = map(int,input().split())
A = [int(input()) for _ in range(m)] #壊れた階段

dp = [0] * (n+1)
dp[0] = 1

for i in range(1,n+1):
    if i in A:
        continue
    x = dp[i-1]
    if i > 1:
        x += dp[i-2]
    dp[i] = x%MOD

print(dp[n])