import sys
input = sys.stdin.readline

MOD = 1000000007
n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]

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

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

print(dp[n])