type aec=array[1..800]of word;
var v:aec;
	a,b,c,r,n:longint;


procedure readdata;
var f:text;
	i,x,j:longint;
begin
assign(f,'nrtri.in'); reset(f);
readln(f,n);

read(f,v[1]);
for i:=2 to n do
		
        begin
        	read(f,x);
            j:=i;
            while (x<v[j-1]) do begin
            	v[j]:=v[j-1];
                dec(j);
            end;
            v[j]:=x;
        end;

close(f);
end;

procedure writedata;
var f:text;
begin
assign(f,'nrtri.out'); rewrite(f);
writeln(f,r);
close(f);
end;

procedure solve;
begin

for a:=1 to n do
	for b:=a+1 to n do
    	for c:=b+1 to n do
        	if (v[a]+v[b]>=v[c]) then inc(r);

end;

Begin
readdata;
solve;
writedata;
End.