n, m = list(map(int, input().split()))
if m > 0:
  a = [int(input()) for i in range(m)]
else:
  a = []

if n = 1:
  pat = 1
else:
  pt = [1]
  if (1 in a):
    pt.append(0)
  else:
    pt.append(1)

  for i in range(2, n + 1):
    if (i in a):
      pt.append(0)
    else:
      if (i-1 in a):
        pt.append(pt[i-2])
      else:
        pt.append(pt[i-1] + pt[i-2])

pat = (pt[-1] % 1000000007)
print(pat)
