1 #include <cmath>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <iostream>
 6 #include <algorithm>
 7  
 8 #define ri register int
 9  
10 #define lim 100000000
11  
12 char *p = new char[lim];
13  
14 template <class T>
15 void read(T &x)
16 {
17     x = 0;
18      
19     while (*p < ‘0‘)++p;
20      
21     while (*p >= ‘0‘)
22         x = x*10 + *p++ - ‘0‘;
23 }
24  
25 #define N 100005
26  
27 int n, m;
28 int w[N];
29 int c[N];
30  
31 int bit[50], cnt[50], tot;
32  
33 int cmp(const void *a, const void *b)
34 {
35     return *(int *)a - *(int *)b;
36 }
37  
38 void get(int t)
39 {
40     if (t > tot)return;
41      
42     if (!cnt[t + 1])get (t + 1);
43      
44     if (cnt[t + 1])--cnt[t + 1], cnt[t] += bit[t + 1] / bit[t];
45 }
46  
47 signed main(void)
48 {
49      
50     fread(p, 1, lim, stdin);
51      
52     read(m); read(n);
53      
54     for (ri i = 1; i <= m; ++i)
55         read(c[i]);
56      
57     for (ri i = 1; i <= n; ++i)
58         read(w[i]);
59          
60     qsort(w + 1, n, sizeof(int), cmp);
61      
62     for (ri i = 1, j = 1; i <= n; i = j)
63     {
64         bit[++tot] = w[i];
65          
66         while (w[i] == w[j])++j;
67     }
68      
69     bit[0] = 1;
70      
71     for (ri i = 1; i <= m; ++i)
72         for (ri j = tot; c[i]; --j)
73             cnt[j] += c[i] / bit[j], c[i] %= bit[j];
74              
75     ri answer = 0;
76              
77     for (ri i = 1, j = 1; i <= n; ++i)
78     {
79         if (bit[j] < w[i])++j;
80          
81         if (!cnt[j])get(j);
82          
83         if (cnt[j])++answer, --cnt[j];
84     }
85      
86     printf("%d\n", answer);
87 }