N, M = map(int, input().split())
a = [int(input()) for i in range(M)] 
z = [0] * (N+1)

def rootCount(x):
     if x in a:
          z[x] = 0
          return 0
     elif x == 0:
          z[x] = 1
          return 1
     elif x == 1:
          z[x] = 1
          return 1
     elif x < N and z[x] != 0:
          return z[x]
     else:
          z[x] = rootCount(x-1) + rootCount(x-2)
          return z[x]
print(rootCount(N) % 1000000007)
