K = int(input())

N = int(input())

X = list(map(int, input().split()))

import sys

sys.setrecursionlimit(10 ** 9)

P = 10 ** 9 + 7

note = [1] + [-1] * K

import bisect

def main(x):
    
    if note[x] != -1:
        
        return note[x]
        
    note[x] = 0
    
    for i in range(bisect.bisect(X, x)):
        
        note[x] += main(x - X[i])
        
        note[x] %= P
    
    return note[x]
    
print(main(K))