https://www.luogu.com.cn/record/95256641

https://www.luogu.com.cn/record/95260815

https://www.luogu.com.cn/record/95261441

https://www.luogu.com.cn/record/95261932

// Problem: P3799 妖梦拼木棒
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/P3799
// Memory Limit: 125 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<iostream>
#include<cmath>
using namespace std;
int w[114514];
bool b[114514];
int lr[4],n;
int ans=0;
void t(int a,int bb){
	if(bb==3){
		/*for(int p=1;p<=n;p++){
			cerr<<b[p];
		}
		cerr<<endl;*/
		if(lr[1]==lr[2]){
			for(int i=1;i<=n-1;i++){
				for(int o=i+1;o<=n;o++){
					//printf("detecting b[%d] & b[%d]!w[%d]=%d,w[%d]=%d,result=%d\n",i,o,i,w[i],o,w[o],w[o]+w[i]);
					if(w[i]+w[o]==lr[1]&&b[i]==0&&b[o]==0){
						//printf("b[%d]==b[%d]=0!\n",i,o);
						ans++;
						ans%=(int)pow(10,9)+7;
					}
				}
			}
		}
		return;
	}else{
		if(b[a]==0){
			for(int i=a;i<=n-(2-bb);i++){
				//cerr<<"limit:"<<n-(4-bb)<<endl;
				b[i]=1;
				lr[bb]=w[i];
				t(i+1,bb+1);
				b[i]=0;
			}
		}
	}
	return;
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>w[i];
	}
	t(1,1);
	cout<<ans<<endl;
	return 0;	
}