#include<stdio.h>
#include<algorithm>
#include<vector>
using namespace std;
int n;
FILE *fin,*fout;
int v[800];

void citire()
{
    int x;
    fin=fopen("nrtri.in","r");
    fscanf(fin,"%d\n",&n);
    for(int i=1;i<=n;i++)
    {
        fscanf(fin,"%d ",&x);
        v[i]=x;
    }
    sort(v+1,v+n+1);
}

int cautare(int li,int ls,int val)
{
    int m,sol=0,p=li;
    printf("%d %d %d\n",v[li],v[ls],val);
    while(li<=ls)
    {
        m=li+(ls-li)/2;
        if(v[m]<=val)
        {
            li=m+1;
            sol=m;
        }
        else
        {
            ls=m-1;
        }
    }

    if(sol!=0)
    sol=sol-p+1;
    printf("%d\n",sol);
    return sol;
}

void afisare(int sol)
{
    fout=fopen("nrtri.out","w");
    fprintf(fout,"%d",sol);
}

void parcurgere()
{
    int i,j,nr=0;
    for(i=1;i<=n;i++)
    {
       // printf("%d\n",v[i]);
        for(j=i+1;j<=n;j++)
        {
            nr+=cautare(j+1,n,v[i]+v[j]);
        }
    }
    afisare(nr);
}

int main()
{
    citire();
    parcurgere();
    return 0;
}