import sys


input = sys.stdin.readline

n, m = map(int, input().split())
broken = set()
for i in range(m):
    a = int(input())
    broken.add(a)

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

for i in range(2, n+1):
    if i in broken:
        pattern[i] = 0
    else:
        pattern[i] = pattern[i-1] + pattern[i-2]

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