import sys

def solve():
    N,M = map(int, input().split())
    
    l = [-1]*(N+1)
    for m in range(M):
        a = int(input())
        l[a] = 0
    if l[1] == 0 and l[2] == 0:
        return 0
    elif l[1] == 0 and l[2] != 0:
        l[2] = 1
    elif l[1] != 0 and l[2] == 0:
        l[1] = 1
    else:
        l[1] = 1
        l[2] = 2
    
    if N == 1:
        return 1
    if N == 2:
        return 2
    
    l.pop(0)
    for i in range(2,N):
        if l[i] == 0:
            continue
        else:
            l[i] = l[i-1] + l[i-2]
    
    return l[-1]%1000000007


if __name__ == '__main__':
    print(solve())