n,m = map(int,input().split())
ans = [1]*n

if n == 1:
    if m == 0:
        print(0)
    else:
        print(1)
else:
    for i in range(m):
        a = int(input())
        ans[a-1] = 0

    if ans[0] != 0 and ans[1] != 0:
        ans[0] = 1
        ans[1] = 2

    for i in range(2,n):
        if ans[i] != 0:
            ans[i] = (ans[i-1] + ans[i-2])%1000000007
        
print(ans[n-1])
