#include<iostream>
#include<algorithm>
#include<fstream>
using namespace std;
int main(){

    ifstream fin("nrtri.in");
    ofstream fout("nrtri.out");

    int s=0,n;
    fin>>n;

    int v[n+1];
    for(int i=0;i<n+3;++i){

        fin>>v[i];
        sort(v,v+n);
    }

    for(int i=0;i<n-2;++i){

        for(int j=i+1;j<n-1;++j){

            for(int z=j+1;z<n;++z){

                if(v[i]+v[j]>=v[z]){

                    ++s;
                }
                else break;
            }
        }
    }

    fout<<s;
}