C++ :

#include<iostream>
#include<string>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
using namespace std;
bool vis[25];
int ans,n,a[25];
void dfs(int l,int sum)
{
    if(sum==40) {ans++;return ;}
    if(l>=n || sum>40) return ;
    if(!vis[l])
    {
        vis[l]=true;
        dfs(l+1,sum+a[l]);
        vis[l]=false;
        dfs(l+1,sum);
    }
}
int main()
{
    while(cin>>n)
    {
          //FILE *f=fopen("输出.txt","a+");
        //cout<<n<<endl;
        for(int i=0;i<n;i++) cin>>a[i];
        ans=0;
        fill(vis,vis+25,false);
        dfs(0,0);
        //fprintf(f,"%d\n",ans);
        cout<<ans<<endl;
        //fclose(f);
    }
    return 0;
}