#include <cstdio>
#include <algorithm>
using namespace std;
FILE *f=fopen("nrtri.in","r");
FILE *g=fopen("nrtri.out","w");
int v[100001],nr;
int main()
{int n,i,j,k,s;
fscanf(f,"%d",&n);
for (i=1;i<=n;i++) fscanf(f,"%d",&v[i]);
sort(v+1,v+n+1);v[n+1]=1000000;


for (i=1;i<n-1;i++) for (j=i+1;j<n;j++)
            {s=v[i]+v[j];

             k=j+1;
             while (k+10<=n&&v[k+10]<s) {nr+=10;
                                         k+=10;}
             while (v[k]<=s) {nr++;
                              k++;}



            }
fprintf(g,"%d\n",nr);
return 0;
}