diff --git a/week4/week4.ino b/week4/week4.ino
index f8ce7f9..073df39 100644
--- a/week4/week4.ino
+++ b/week4/week4.ino
@@ -6,28 +6,29 @@ void setup() {
 void loop() {
 	int len = 0;
 	int seq[1000];
+	while (len < 3) seq[len++] = random(0, 4); // generate 3 random numbers
 	while (1) {
-		seq[len++] = random(0, 4);
-		for (int i = 0; i < len; ++i) {
-			digitalWrite(seq[i]<<1|1, HIGH);
+		seq[len++] = random(0, 4); // generate another random number
+		for (int i = 0; i < len; ++i) { // flash the LEDs according to seq
+			digitalWrite(2*seq[i]+1, HIGH);
 			delay(500);
-			digitalWrite(seq[i]<<1|1, LOW);
+			digitalWrite(2*seq[i]+1, LOW);
 			delay(500);
 		}
 		for (int i = 0; i < len; ++i) {
-			while (analogRead(A0) < 240 && analogRead(A1) < 240 && analogRead(A2) < 240 && analogRead(A3) < 240);	
-			for (int j = 0; j < 4; ++j)
+			while (analogRead(A0) < 240 && analogRead(A1) < 240 && analogRead(A2) < 240 && analogRead(A3) < 240); // wait for press
+			for (int j = 0; j < 4; ++j) // check which button was pressed and whether it matches seq
 				if (analogRead(A0+j) > 240 && seq[i] != j) goto DONE; // Legit use case of goto to jump out of 3 loops
-			delay(500);
+			delay(250);
 		}
-		for (int i = 0; i < 8; ++i) {
-			for (int j = 0; j < 4; ++j) digitalWrite(j<<1|1, i&1^1);
+		for (int i = 0; i < 8; ++i) { // flash green lights 4 times
+			for (int j = 0; j < 4; ++j) digitalWrite(2*j+1, (i+1)%2);
 			delay(100);
 		}
 	}
 	DONE:
-	for (int i = 0; i < 8; ++i) {
-		for (int j = 0; j < 4; ++j) digitalWrite(j<<1, i&1^1);
+	for (int i = 0; i < 8; ++i) { // flash red lights 4 times
+		for (int j = 0; j < 4; ++j) digitalWrite(2*j, (i+1)%2);
 		delay(100);
 	}
 }