#include <cstdio>
  #include <algorithm>
  #include<cstdlib>
   //#define max(a,b) (a>b)? a:b
using namespace std;
 FILE*fin=fopen("nrtri.in","r");
  FILE*fout=fopen("nrtri.out","w");
   int a,b,i,j,k,n,m,v[1000],rasp;
   //bool cmp (int a, int b){ return (a>b);}

    int main()
    {
        fscanf(fin,"%d",&n);
             for (i=1;i<=n;i++)
                  fscanf(fin,"%d",&v[i]);
         sort(v+1,v+n+1);
    for (i=1;i<n-1;i++)
        for (j=i+1;j<=n-1;j++)
            rasp+=std::distance(upper_bound(v+j+1,v+n+1,v[j]+v[i]),lower_bound(v+j+1,v+n+1,v[i]-v[j]));
    fprintf(fout,"%d\n",abs(rasp));
    return 0;
    }