diff --git a/include.hh b/include.hh
index 275b489..89a2c9a 100644
--- a/include.hh
+++ b/include.hh
@@ -67,6 +67,7 @@ using tiid = tuple<int, int, ld>;
 using tiii = tuple<int, int, int>;
 template <typename T> using max_heap = priority_queue<T>;
 template <typename T> using min_heap = priority_queue<T, vector<T>, greater<>>;
+template <typename T> using oi = ostream_iterator<T>;
 
 /* constants */
 constexpr int INF = 0x3f3f3f3f;