import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.NoSuchElementException;
import java.util.Scanner;

import java.util.*;
public class Main { //クラス名はMain
    public static void main(String[] args) {
        //Scanner sc=new Scanner(System.in);
       FastScanner sc=new FastScanner();
        int n=sc.nextInt();
        long counter=0;
        PriorityQueue<Integer> pq = new PriorityQueue<>(Collections.reverseOrder());
        for(int i=0;i<n;i++){
        	pq.add(sc.nextInt());
        }
        ArrayList<Integer> ar=new ArrayList<>();
        for(int i=0;i<n;i++){
        	ar.add(pq.poll());	//大きい順に並ぶ
        }
        for(int i=0;i<n-2;i++){
        	int c=ar.get(i);
            int size=ar.size();
            for(int j=i+1;j<n-1;j++){              
            	int b=ar.get(j);
                if(2*b<c)break;
                for(int k=j+1;k<n;k++){
                	int a=ar.get(k);
                    if(c<a+b){
                    	counter++;
                    }else{
                    	break;
                    }
                }
            }
        }
        
        System.out.println(counter);
    }
}

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble() { return Double.parseDouble(next());}
}

Measured memory_bytes: 22996