n,m = map(int,input().split())
a = [int(input()) for _ in range(m)]
mod = 10**9+7
memo = [-1]*(n+1)
def rec(x):
    if memo[x] != -1: pass
    elif x == 0: memo[x] = 1
    elif a and x == a[-1]:
        memo[x] = 0
        a.pop()
    elif x == 1: memo[x] = 1
    else: memo[x] = rec(x-1)+rec(x-2)
    return memo[x]%mod
print(rec(n))