import sys
input = sys.input.readline

MOD = 1000000007

n , m = map(int,input().split())

count = [-1] * (n+1)
for i in range(m):
    count[int(input())] = 0

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

print(count[n])
