cost.plot.name = "vrptw.png"
png(filename = cost.plot.name, width = 500, height = 400)
plot_dronetruck_kvehicle2(vrptr)
dev.off()


cost.plot.name = "vrpdtw.png"
png(filename = cost.plot.name, width = 500, height = 400)
plot_dronetruck_kvehicle2(best.truck.routes, best.drone.routes)
dev.off()
