diff --git a/homework4.txt b/homework4.txt
index d8160f0..91e6837 100644
--- a/homework4.txt
+++ b/homework4.txt
@@ -1,2 +1,4 @@
-1. What is .gitignore? You can write the answer either in Korean or English.
-2. Why do Github users need an SSH key pair? (Users can use either SSH key pair or github account info.) Please write down a brief explanation of SSH key.
\ No newline at end of file
+1. What is .gitignore? You can write the answer either in Korean or English. 
+.git ignore À̶õ Project¿¡ ¿øÇÏÁö ¾Ê´Â Backup FileÀ̳ª Log File , ȤÀº ÄÄÆÄÀÏ µÈ ÆÄÀϵéÀ» Git¿¡¼­ Á¦¿Ü½Ãų¼ö ÀÖ´Â ¼³Á¤ FileÀÌ´Ù.
+2. Why do Github users need an SSH key pair? (Users can use either SSH key pair or github account info.) Please write down a brief explanation of SSH key. 
+SSH key¸¦ ÀÌ¿ëÇÏ¸é ºñ¹Ð¹øÈ£ º¸´Ù ´õ ³ôÀº º¸¾È¼öÁØÀ» °¡Áú ¼ö ÀÖÀ¸¸ç ·Î±×ÀÎ ¾øÀ̵µ ¼­¹ö¿¡ Á¢¼ÓÇÒ ¼ö ÀÖ´Ù.
diff --git a/homework4/2019-12472.zip b/homework4/2019-12472.zip
new file mode 100644
index 0000000..145b1ac
Binary files /dev/null and b/homework4/2019-12472.zip differ
diff --git a/homework4/Source.cpp b/homework4/Source.cpp
index ab69b66..08e711a 100644
--- a/homework4/Source.cpp
+++ b/homework4/Source.cpp
@@ -25,10 +25,14 @@ int main()
 	int* output = new int[arrsize];
 	cout << "Array output: ";
 
-	/***********************************
-	Implement the code here!
-	************************************/
-
+	for (int i = 0; i < arrsize; i++){
+		output[i] = 0;
+		for (int j = 0; j < arrsize; j++) {
+			if (arr[i] > arr[j]) {
+				output[i] += 1;
+			}
+		}
+	}
 	for (int i = 0; i < arrsize; i++) {
 		cout << output[i] << " ";
 	}