program p1;
var f,g:text;
    x:array[1..100] of integer;
    i,n,a,b,c,nr,j,l:integer;
begin
     assign(f,'nrtri.in');reset(f);
     assign(g,'nrtri.out');rewrite(g);
     read(f,n);
     for i:=1 to n do read(f,x[i]);
     nr:=0;
     for i:=1 to n-2 do
         for j:=i+1 to n-1 do
             for l:=j+1 to n do
                 begin
                      a:=x[i];
                      b:=x[j];
                      c:=x[l];
                      if (a+b>=c)and(a+c>=b)and(b+c>=a) then nr:=nr+1;
                 end;
     writeln(g,nr);
     close(f);
     close(g);
end.