initialize turn at 0

src/backend/Board.java

@@ -26,7 +26,7 @@ public class Board {
 	}
 
 	public int getTurnNumber() {
-		turn = 1;
+		turn = 0;
 		for (int i = 1; i<=n; i++) {
 			if (n%i == 0) {
 				turn += 1;