#include <fstream>
#include<algorithm>
using namespace std;
ifstream in("nrtri.in");
ofstream out("nrtri.out");
int main()
{
    int v[2001],n,i,nrtri=0;
    in>>n;
    for(i=1;i<=n;i++)
    {
        in>>v[i];
    }
    sort(v+1,v+n+1);
    for(i=1;i<=n;i++)
    {
        if(v[i]+v[i+1]>v[i+2])
            nrtri++;
        if(v[i]+v[i+1]==v[i+2])
            nrtri++;
        if(i==n-1)
                break;
    }
    out<<nrtri;
    return 0;
}