#include<iostream>
#include<fstream>
using namespace std;
int main ()
{
    ifstream f("nrtri.in");
    ofstream g("nrtri.out");
    int i,n,a,b,v[800],ok,msk,c=0,x,pos,aux,j;
    f>>n;
    for(i=1;i<=n;i++)
    {
        f>>v[i];
    }
    do
    {
        ok=1;
        for(i=1;i<=n-1;i++)
        {
            if(v[i]>v[i+1])
            {
                ok=0;
                aux=v[i];
                v[i]=v[i+1];
                v[i+1]=aux;
            }
        }
    } while(ok!=1);
    for(i=1;i<=n;i++)
    {
        a=v[i];
        for(j=i;j<=n;j++)
        {
            b=v[j];
            x=v[j+1];
            pos=0;
            for(msk=1<<20;msk>0;msk/=2)
            {
                if((pos+msk<=n)&&(v[pos+msk]<=x))
                {
                    pos+=msk;
                }
            }
            if((v[pos]==x)&&(x<a+b))
            {
                c++;
            }

    }
    }
    g<<c;
    return 0;

}