import sys
input = sys.stdin.readline

N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
base = 1_000_000_007

x = [0] * (N+1)
x[0] = 1
ai = 0
if ai >= M or 1 != a[ai]:
    x[1] = x[0]
else:
    ai += 1
for i in range(2, (N+1)):
    if ai >= M or i != a[ai]:
        x[i] = (x[i-1] + x[i-2]) % base
    else:
        ai += 1
print(x[N])