Running a node with rosrun requires extra input?

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I'm trying to make OpenCV work with ROS and I finally found something that compiles, therefore I just downloaded and catkin_make this. It did build, however, when I run rosrun buoy buoycv, I'm asked to choose one of the next ones additionally: build/, devel/, install/ or src/ and I do not understand why, nor I could find an explanation or have encountered this before.

Could somebody kindly provide me with information about this? As of now, I cannot launch the node because of this.

Thank you in advance