var n,i,j,nr,aux,k:longint;
    a:array[1..800] of longint;
    f:text;
begin
assign(f,'nrtri.in');reset(f);
read(f,n);
for i:=1 to n do begin
                 read(f,a[i]);
                 j:=i;
                 while j>0 do begin
                              if a[j]<a[i] then begin
                                                aux:=a[i];
                                                a[i]:=a[j+1];
                                                a[j+1]:=aux;
                                                break;
                                                end;
                              j:=j-1;
                              end;
                 end;
close(f);
nr:=0;
for i:=1 to n-2 do
    for j:=i+1 to n-1 do
        for k:=j+1 to n do
    if a[i]+a[j]>=a[k] then inc(nr);
assign(f,'nrtri.out');rewrite(f);
writeln(f,nr);
close(f);
end.