Hello, I am trying to find the intersection points of the two horizontal solid lined with the dashed line. I would like to label each point as for example point a and the second point as b. I would also like to display the value of the intersecting point. Note that I am aiming to find the x value of the intersecting point since I know y. I find it easier with function and using Plot function. I tried with this one but it didn't work. Thank you

list1 = {0, 1};
list2 = {0, 5};
ListLinePlot[Transpose[{list1, list2}], PlotStyle -> {Thick, Dashed}, 
 PlotRange -> {{0, 5}, {0, 5}}, 
 GridLines -> {None, {{2, {Black, Thick}}, {4, {Green, Thick}}}}]