#include<stdio.h>
bool tri(int a,int b,int c)
{
	if( b+c>=a  && a+c>=b && b+a>=c )
		return true;
	return false;
}
int main()
{
	int N,v[801],a,b,c,m=0,z=0;
	freopen("nrtri.in","r",stdin);
	freopen("nrtri.out","w",stdout);
	scanf("%d",&N);
	for(;N;--N,++m)
		scanf("%d",&v[m]);
	for(a=0;a<m-2;++a)
		for(b=a+1;b<m-1;++b)
			for(c=b+1;c<m;++c)
				if(tri(v[a],v[b],v[c])==true)
					z++;
	printf("%d\n",z);
	return 0;
}