#include<stdio.h>
#include<stdlib.h>
int fcmp(const void* a,const void* b)
{
	return *(int*)a-*(int*)b;
}
int main()
{
   FILE *f=fopen("nrtri.in","r");
   int n,i;
   long a[800],sol=0,var;
   fscanf(f,"%d",&n);
   for(i=0;i<n;++i)
   fscanf(f,"%d",&a[i]);

   fclose(f);
   qsort(a,n,sizeof(long),fcmp);

   int k=0,j,ok;
   for(k;k<n-2;++k)
   {
	  for(i=k+1;i<n-1;++i)
	  {
		  var=a[i]+a[k];ok=1;
		  for(j=i+1;j<n&&ok;++j)
		  if(a[j]>var)ok=0;
		  else sol++;
	  }
   }
   FILE*g=fopen("nrtri.out","w");
   fprintf(g,"%d",sol);
   fclose(g);
   return 0;
}