n, m = map(int, input().split())
 
a_list=[]
 
for index in range(m):
    a_list.append(int(input()))
 
ans_list=[]
 
for index in range(n + 1):
    ans_list.append(0)
 
for index in range(n + 1):
    if index == 0:
        ans_list[index] += 1
        continue
    if index == 1 and (index not in a_list):
        ans_list[index] += ans_list[index - 1]
        continue
    
    if index not in a_list:
        if (index - 1) not in a_list:
            ans_list[index] += ans_list[index - 1]
            ans_list[index] %= 1000000007
        if (index - 2) not in a_list:
            ans_list[index] += ans_list[index - 2]
            ans_list[index] %= 1000000007
 
print(ans_list[n])
