var v:array[1..801] of integer;
    n,i,j,k,nr:integer;
    f:text;

procedure cit;
begin
assign(f,'nrtri.in');reset(f);
readln(f,n);
for i:=1 to n do read(f,v[i]);
close(f);
end;

procedure det;
begin
for i:=1 to n-2 do
    for j:=i+1 to n-1 do
        for k:=j+1 to n do
            if(v[i]<=v[j]+v[k])and(v[j]<=v[i]+v[k])and(v[k]<=v[i]+v[j]) then
              nr:=nr+1;
end;

procedure afs;
begin
assign(f,'nrtri.out');rewrite(f);
writeln(f,nr);
close(f);
end;

begin
cit;
det;
afs;
end.