+
−a = int( raw_input( 'Enter number: ') )
+
−while a != 4:
+
−    print a
+
−    if a % 2 == 1:
+
−        a = a * 3 + 1
+
−    else:
+
−        a /= 2
+
−print 4
+
−print 2
+
−print 1