#include <stdio.h>

using namespace std;
unsigned n,a[1000],k,i,j,z;
int main()
{
    FILE*f;
    f=fopen("nrtri.in","r");
    fscanf(f,"%d",&n);
    for(i=0;i<n;i++) fscanf(f,"%u",&a[i]);
    fclose(f);
    for(i=0;i<n;i++)
        for(j=i+1;j<n;j++)
            for(k=j+1;k<n;k++)
                if(a[i]<a[j]+a[k]&&a[j]<a[k]+a[i]&&a[k]<a[j]+a[i]) z++;
    FILE*g;
    g=fopen("nrtri.out","w");
    fprintf(g,"%u",z);
    fclose(g);
    return 0;
}