Fix bad inclusion cause code not compiling.

1 files changed, 1 insertions, 0 deletions

diff --git a/vec.h b/vec.h
index 64eaaca..c7669bf 100644
--- a/vec.h
+++ b/vec.h
@@ -7,6 +7,7 @@
 
 #include <cmath>
 #include <random>
+#include <ostream>
 
 static inline bool eq(int a, int b) {
     return a == b;