A plumber performs an annual check of the pipe system of a house. The measuring system has counted the amount of water that passes through each pipe. It has been discovered that some connecting points have leaks, so not all of the water that gets to these point flows on into the next pipes. Obviously, this situation is not normal, so the plumber has made a decision to repair the system.
Which connecting points should be repaired?
Note: enter the numbers of the connecting points separated by a space symbol, for example: 2 3 7.