package main

import (
	"fmt"
	"strings"

	"internal/tree"
	"internal/util"
)

func main() {
	data := util.ReadInput()

	// Build a tree of dependencies.
	root := tree.BuildDependencyTree(data)

	// Walk the tree and determine the correct ordering.
	order := tree.FindOrder(root)

	output := strings.Builder{}
	for _, node := range order {
		if node.Name == 0 {
			continue
		}

		output.WriteRune(node.Name)
	}
	fmt.Println(output.String())
}