#!/usr/bin/env python3

import sys

P_NUM = 1000000007


def solv(n, m, a):
    comb_m2 = 1
    if 1 in a:
        comb_m1 = 0
    else:
        comb_m1 = 1

    for i in range(2, n+1):
        if i in a:
            comb = 0
        else:
            comb = (comb_m1 + comb_m2) % P_NUM
        
        comb_m1, comb_m2 = comb, comb_m1

    return comb


if __name__ == '__main__':

    n, m = map(int, input().split())
    if m:
        a = set(map(int, sys.stdin))
    else:
        a = set()

    ans = solv(n, m, a)

    print(ans)
