# include <stdio.h>
int main (){
	int n,i,j,a[800],k,nr=0;
	freopen("nrtri.in","r",stdin);
	freopen("nrtri.out","w",stdout);
	scanf("%d",&n);
	for(i=0;i<n;i++)
		scanf("%d",&a[i]);
	for(i=0;i<n;i++);
		for(j=0;j<n;j++)
			for(k=0;k<n;k++)
				if((a[i]+a[j]>=a[k]) && (a[i]+a[k]>=a[j]) && (a[k]+a[j]>=a[i])){
					nr++;
				}
	printf("%d",nr/2);
	return 0;
}