#include<cstdio>
#include<algorithm>
using namespace std;
FILE *f,*g;
int nr,i,j,n,k,a[801];
int tri(int a,int b,int c)
{if(a+b>=c&&b+c>=a&&c+a>=b)
return 1;
else
return 0;
}
int valid(int a,int b,int c)
{if(c>a+b)
	return 1;
return 0;
}
int main()
{f=fopen("nrtri.in","r");
g=fopen("nrtri.out","w");
fscanf(f,"%d",&n);
for(i=1;i<=n;++i)
fscanf(f,"%d",&a[i]);
nr=0;
sort(a+1,a+n+1);
for(i=1;i<n-1;++i)
	for(j=i+1;j<n;++j)
		for(k=j+1;k<=n;++k)
			if(tri(a[i],a[j],a[k])==1)
				++nr;
			else
				if(valid(a[i],a[j],a[k]))
					break;
fprintf(g,"%d\n",nr);
fclose(f);
fclose(g);
return 0;
}