program testtr;
type vect = array [1..800] of 1..30001;
var A : vect;
    i,j,l,n : 1..800;
    S : 0..1000000;
    f : text;
    ok : boolean;
begin
assign(f,'nrtri.in');
reset(f);

readln(f,n);
for i :=  1 to n do
read(f,A[i]);

close(f);

S := 0;

for i := 1 to n-2 do
for j := i+1 to n-1 do
for l := j+1 to n do begin
ok := true;
if A[i]+A[j]<A[l] then ok := false;
if A[j]+A[l]<A[i] then ok := false;
if A[l]+A[i]<A[j] then ok := false;
if ok then inc(S);
end;

write('S=',S);

assign(f,'nrtri.out');
rewrite(f);

write(f,S);

close(f);

end.