#include<cstdio>

long i,j,k,n,numar;

int a[30001];

int triunghi(long b,long c,long d)
{
	
	if (a[b]+a[c]<a[d]) return 0;
	if (a[c]+a[d]<a[b]) return 0;
	if (a[d]+a[b]<a[c]) return 0;
	return 1;
	
}

int main()
{
	freopen("nrtri.in","r",stdin);
	freopen("nrtri.out","w",stdout);
	scanf("%ld", &n);
	for (i=1;i<=n;i++)
	scanf("%ld", &a[i]);
	
	for (i=1;i<n-1;i++)
		for (j=i+1;j<n;j++)
			for (k=j+1;k<=n;k++)
				if (triunghi(i,j,k)) numar++;


	printf("%ld", numar);
	
	return 0;
	
}