#include <stdio.h>
int main()
{
	int n,d=0,i,j,l,a;
	short int e[30000];
	FILE *f1,*f2;
	f1=fopen("nrtri.in","r");
	f2=fopen("nrtri.out","w");
	fscanf(f1,"%d",&n);
	for(i=1;i<=n;i++)
	{
		fscanf(f1,"%d",&a);
		e[a]++;
	}
	for(i=1;i<=30000;i++)
	{
		if(e[i]==1)
		{
			for(j=i+1;j<=30000;j++)
				if(e[j])
					for(l=j;l<i+j;l++)
						if(e[l])	d++;
		}
		if(e[j]>1)
		{
			for(j=i;j<=30000;j++)
				if(e[j])
					for(l=j;l<i+j;l++)
						if(e[l])	d++;
		}
			
	}
	
	fprintf(f2,"%d",d);
	fclose(f1);
	fclose(f2);
	return 0;
}