diff --git a/12dec/input_test b/12dec/input_test
new file mode 100644
index 0000000..71c34d4
--- /dev/null
+++ b/12dec/input_test
@@ -0,0 +1,7 @@
+0 <-> 2
+1 <-> 1
+2 <-> 0, 3, 4
+3 <-> 2, 4
+4 <-> 2, 3, 6
+5 <-> 6
+6 <-> 4, 5
diff --git a/12dec/main.go b/12dec/main.go
new file mode 100644
index 0000000..772cc6d
--- /dev/null
+++ b/12dec/main.go
@@ -0,0 +1,94 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type Prog struct {
+	Num int
+	Cx  []*Prog
+}
+
+var (
+	Progs map[int]*Prog
+)
+
+func main() {
+	sc := bufio.NewScanner(os.Stdin)
+	Progs = make(map[int]*Prog)
+	for sc.Scan() {
+		fmt.Println(sc.Text())
+		parse(sc.Text())
+	}
+	nums := make([]int, 0, 0)
+	nums = walk(Progs[0], nums)
+	fmt.Println("result ", len(nums))
+}
+
+func appendUniq(nums []int, num int) ([]int, bool) {
+	for _, n := range nums {
+		if n == num {
+			return nums, false
+		}
+	}
+	nums = append(nums, num)
+	return nums, true
+}
+
+func walk(p *Prog, nums []int) []int {
+	var added bool
+	nums, added = appendUniq(nums, p.Num)
+	if added {
+		for _, pp := range p.Cx {
+			nums = walk(pp, nums)
+		}
+	}
+	return nums
+}
+
+func parse(in string) {
+	expr := strings.Split(in, " <-> ")
+	num, _ := strconv.Atoi(expr[0])
+	p1 := GetProg(num)
+
+	list := strings.Split(expr[1], ", ")
+	for _, l := range list {
+		nl, _ := strconv.Atoi(l)
+		p2 := GetProg(nl)
+		Pipe(p1, p2)
+		Pipe(p2, p1)
+	}
+}
+
+func NewProg(num int) *Prog {
+	return &Prog{
+		num,
+		make([]*Prog, 0, 0),
+	}
+}
+
+func GetProg(num int) *Prog {
+	p := Progs[num]
+	if p == nil {
+		p = NewProg(num)
+		Progs[num] = p
+	}
+	return p
+}
+
+func Pipe(p1, p2 *Prog) {
+	piped := false
+	for _, p := range p1.Cx {
+		if p1.Num == p.Num {
+			piped = true
+		}
+	}
+	if !piped {
+		p1.Cx = append(p1.Cx, p2)
+		fmt.Println("pipe", p1.Num, p2.Num)
+	}
+}