import sys
sys.setrecursionlimit(10 ** 6)

n, m = [int(i) for i in input().split()]
fibo_l = [1] + [None] * n
a = [int(input()) for i in range(m)]

def fibo(x):
    if x not in a and x >= 0:
            if fibo_l[x] is None:
                fibo_l[x] = fibo(x-1) % 1000000007 + fibo(x-2) % 1000000007
            return fibo_l[x]
    else: return 0
    
print(fibo(n) % 1000000007)
