#include <fstream>
#include <iostream>
#include <stdlib.h>

using namespace std;

int sort(const void *a,const void* b)
{
return *(int*)a-*(int*)b;
}
int n,a[801],sol;

int cond(int i,int j,int k)
{
return a[i]+a[j]>=a[k]&&a[i]+a[k]>=a[j]&&a[j]+a[k]>=a[i];


}

int main()
{int i,j,k;
ifstream in("nrtri.in");
in>>n;
for(i=1;i<=n;i++)in>>a[i];
in.close();
qsort(a+1,n,sizeof(a[0]),sort);
for(i=1;i<=n-2;i++)
for(j=i+1;j<=n-1;j++)
for(k=j+1;k<=n;k++)
if(cond(i,j,k))sol++;
	else break;
ofstream out("nrtri.out");
out<<sol<<'\n';
out.close();
return 0;
}