diff --git a/nodup.py b/nodup.py
new file mode 100644
index 0000000..9638c0f
--- /dev/null
+++ b/nodup.py
@@ -0,0 +1,3 @@
+words = input().strip().split()
+unique_words = set(words)
+print("yes" if len(words) == len(unique_words) else "no")