課堂練習2

size 500 500
paper 30 75 200
field 0 0 450 450 10
field 0 0 400 400 20
field 0 0 350 350 30
field 0 0 300 300 40
field 0 0 250 250 50
field 0 0 200 200 60
field 0 0 150 150 70
field 0 175 50 225 55
field 0 275 50 325 65
field 0 375 50 425 75
field 50 225 100 275 30
field 50 325 100 375 100
field 100 275 150 325 0