% problem E

const maxX = 100. 
const maxY = 100. 

source(30,40). 
sink(0,10,40).
sink(1,50,50).
sink(2,40,10).
sink(3,0,30).

obstacle(30,50,20..30).
obstacle(50,60,30..40).
obstacle(70,90,0..10).
obstacle(80,90,10..20).
obstacle(80,90,20..30).
obstacle(80,90,30..40).
obstacle(60,70,60..70).
obstacle(60,90,70..80).
obstacle(10,30,50..60).
obstacle(20,40,60..70).
obstacle(20,30,70..80).
obstacle(20,30,80..90).