N, M = map(int,input().split())
A_list = []
for i in range(M):
    A_list.append(int(input()))
if A_list:
    if A_list[0] == 1:
        Dp_list = [1,0]
    else:
        Dp_list = [1,1]
else:
    Dp_list = [1,1]
if N != 1:
    for i in range(2, N + 1):
        if i not in A_list:
            Dp_list.append(Dp_list[i-2] + Dp_list[i-1])
        elif i in A_list and i-1 in A_list:
            Dp_list = [0] * (N + 1)
            break
        else:
            Dp_list.append(0)
        if Dp_list[i] > 1000000007:
            Dp_list[i] -= 1000000007
    print(Dp_list[N]%1000000007)
else:
    print(1)