1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #include<cmath>
 5 
 6 using namespace std;
 7 const int N=110;
 8 
 9 int a[N];
10 
11 inline int read()
12 {
13     int x=0,f=1;
14     char c=getchar();
15     while(c<‘0‘||c>‘9‘) {if(c==‘-‘)f=-1; c=getchar();}
16     while(c>=‘0‘&&c<=‘9‘)x=x*10+c-‘0‘,c=getchar();
17     return x*f;
18 }
19 
20 int main()
21 {
22     
23     freopen("countb.in","r",stdin);
24     freopen("countb.out","w",stdout);
25     int n=read();
26     for(int i=1;i<=n;i++)
27         a[i]=read();
28         
29     sort(a+1,a+n+1);
30     
31     int Answer=0;
32     for(int i=1;i<=n;i++)
33     {
34         bool flag=1;
35         for(int j=i-1;j>=1&&flag;j--)
36         {
37             for(int k=1;k<=i-1&&flag;k++)
38             {
39                 if(a[j]+a[k]==a[i]&&k!=j)
40                 {
41                     Answer++;
42                     flag=0;
43                 }
44             }
45         }
46     }
47     printf("%d",Answer);
48     return 0;
49     
50 }