[apuhach@latitude SegmentTree]$ git diff basic.h
diff --git a/DataStructures/SegmentTree/basic.h b/DataStructures/SegmentTree/basic.h
index 72d3f9e..cfd74c8 100644
--- a/DataStructures/SegmentTree/basic.h
+++ b/DataStructures/SegmentTree/basic.h
@@ -1,12 +1,14 @@
 /*
 struct SegTreeOps {
-    T combine(T a, T b);
-    T update(T cur, UPD val);
+    static T combine(T a, T b);
+    static T update(T cur, UPD val);
 };
  */
-template<typename OPS, typename T, typename UPD>
+template<typename OPS, typename UPD>
 class SegTree {
 public:
+    using T = typename result_of<OPS::combine>::type;
+
     SegTree(int n): data(4*n), n(n) {
     }