#include <stdio.h>

int main()
{

int n,v[800],j,k;
long ct=0;

freopen("nrtri.in","r",stdin);
freopen("nrtri.out","w",stdout);

scanf("%d",&n);
for (int i=1;i<=n;i++) scanf("%d",&v[i]);

for (i=1;i<n;i++)
 for (j=i+1;j<=n;j++) if (v[i]>v[j]) v[i]=v[j]+v[i]-(v[j]=v[i]);

for (i=1;i<n-1;i++)
 for (j=i+1;j<n;j++)
  for (k=j+1;k<=n;k++)
    if (v[i]+v[j]>=v[k]) ct++;

printf("%ld",ct);
return 1;
}