var a:array[1..30000] of integer;
aux,i,j,n,k:integer;
nr:longint;
f,g:text;
ok:boolean;
begin
assign(f,'nrtri.in');reset(f);
assign(g,'nrtri.out');rewrite(g);
readln(f,n);
nr:=0;
for i:=1 to n do read(f,a[i]);
repeat
ok:=true;
for i:=1 to n-1 do
if a[i]>a[i+1] then
begin
ok:=false;
aux:=a[i];
a[i]:=a[i+1];
a[i+1]:=aux;
end;
until ok=true;
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]>0) and (a[j]<>0) and (a[k]<>0) and
(a[i]+a[j]>=a[k]) and (a[k]+a[j]>=a[i]) and (a[i]+a[k]>=a[j]) then inc(nr);
write(g,nr);
close(f);
close(g);
end.