import sys
sys.setrecursionlimit(1000000000)
input = sys.stdin.readline

N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
mem = [0] * N
def count_steps(n):
    if mem[n-1]:
        return mem[n-1]
    elif n - 1 in a and n - 2 in a:
        return 0
    elif n - 1 in a:
        if n > 2:
            mem[n-1] = count_steps(n-2)
            return mem[n-1]
        else:
            mem[1] = 1
            return 1
    elif n - 2 in a:
        mem[n-1] = count_steps(n-1)
        return mem[n-1]
    elif n == 1:
        mem[0] = 1
        return 1
    elif n == 2:
        mem[1] = 2
        return 2
    else:
        mem[n-1] = (count_steps(n-1) + count_steps(n-2)) % 1000000007
        return mem[n-1]
print(count_steps(N))