#include<stdio.h>
#include<algorithm>
#include<vector>
int v[801],n,i,j,nr,h,sum;
int main (){
    FILE *fin=fopen("nrtri.in","r"),*fout=fopen("nrtri.out","w");
    fscanf(fin,"%d",&n);
    for(i=1;i<=n;i++) {
fscanf(fin,"%d",&v[i]);
}
    sort(v,v+n+1);
    for(i=1;i<=n-2;i++)
    for(j=i+1;j<=n-1;j++){
sum=a[i]+a[j];
    for(h=j+1;h<=n;h++)
        if(sum>=a[h]) nr++;
        else h=n+1;
}
    fprintf(fout,"%d",nr);
    return 0;
}