diff --git a/src/IntListTest.java b/src/IntListTest.java
new file mode 100644
index 0000000..826b60e
--- /dev/null
+++ b/src/IntListTest.java
@@ -0,0 +1,83 @@
+import java.util.ArrayList;
+import java.util.Scanner;
+
+public class IntListTest {
+
+	public static void main(String[] args) {
+		new IntListTest();
+	}
+
+	Scanner scan;
+	IntListTest(){
+		scan = new Scanner(System.in);
+		AvgIL intlist = new AvgIL();
+		System.out.println("Input integer or n|sum|avg|list|exit");
+		while(true) {
+			String in = scan.next();
+			if ( in.equals("exit") ) {
+				System.exit(0);
+			} else if ( in.equals("list") ) {
+				intlist.show();
+			} else if ( in.equals("n") ) {
+				System.out.println("n="+intlist.size());
+			} else if ( in.equals("sum") ) {
+				System.out.println("sum="+intlist.getSum());
+			} else if ( in.equals("avg") ) {
+				System.out.println("avg="+intlist.getAvg());
+			} else if ( in.matches("[0-9]+") ){ // Int value
+				int num = Integer.parseInt(in);
+				intlist.add(num);
+//				System.out.println("sum="+intlist.getSum()+" avg="+intlist.getAvg()+" n="+intlist.size());
+			}
+		}
+	}
+}
+
+class IntList {
+	protected ArrayList<Integer> intlist; // storage of int values
+	IntList(){
+		intlist = new ArrayList<Integer>();
+	}
+	public void add(int n) {
+		intlist.add(n);
+	}
+	public int size() {
+		return intlist.size();
+	}	
+	public void show() {
+		for(int k: intlist) {
+				System.out.print(k+" ");
+		}
+		System.out.println("");
+	}
+}
+
+class SumIL extends IntList {
+	protected float sum = 0;
+
+	public void add(int n) {
+		super.add(n);
+		// update sum
+		sum = 0;
+        // for(int i=0; i<n ; i++){ }
+		for(int k: intlist) {
+			sum += k;
+		}
+	}
+	public float getSum() {
+		return sum;
+	}
+}
+
+class AvgIL extends SumIL {
+	private float avg = 0;
+
+	public void add(int n) {
+		super.add(n);
+		// update avg
+		avg = sum / size();
+	}
+	public float getAvg() {
+		return avg;
+	}
+}