#1行目
width = input()

#2行目
blocknum = input()
split_blocknum=blocknum.split()

#3行目
blocksize = input()
split_blocksize=blocksize.split()

blocksize_list = sorted(split_blocksize)

for n in blocksize_list:
    if sum_blocksize + n <= width:
        sum_blocksize += n
        inblock += 1
    else:
        break
        
print(inblock)