diff --git a/20201228/main.go b/20201228/main.go
new file mode 100644
index 0000000..d5014da
--- /dev/null
+++ b/20201228/main.go
@@ -0,0 +1,37 @@
+package main
+
+import (
+	"strings"
+)
+
+func main() {
+
+}
+
+func transform(s string) []string {
+	return process(strings.Split(s, " "))
+}
+
+func process(src []string) []string {
+	maxL := 0
+	for _, s := range src {
+		if len(s) > maxL {
+			maxL = len(s)
+		}
+	}
+	mid := make([]string, maxL)
+	for i := 0; i < len(mid); i++ {
+		for _, s := range src {
+			if i < len(s) {
+				mid[i] += string(s[i])
+			} else {
+				mid[i] += " "
+			}
+		}
+	}
+	var ret []string
+	for _, s := range mid {
+		ret = append(ret, strings.TrimRight(s, " "))
+	}
+	return ret
+}
diff --git a/20201228/main_test.go b/20201228/main_test.go
new file mode 100644
index 0000000..388fe4b
--- /dev/null
+++ b/20201228/main_test.go
@@ -0,0 +1,74 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_process(t *testing.T) {
+	type args struct {
+		src []string
+	}
+	tests := []struct {
+		name string
+		args args
+		want []string
+	}{
+		{
+			"test1",
+			args{[]string{"HOW", "ARE", "YOU"}},
+			[]string{"HAY", "ORO", "WEU"},
+		},
+		{
+			"test2",
+			args{[]string{"TO", "BE", "OR", "NOT", "TO", "BE"}},
+			[]string{"TBONTB", "OEROOE", "   T"},
+		},
+		{
+			"test3",
+			args{[]string{"CONTEST", "IS", "COMING"}},
+			[]string{"CIC", "OSO", "N M", "T I", "E N", "S G", "T"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := process(tt.args.src); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("process() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_transform(t *testing.T) {
+	type args struct {
+		s string
+	}
+	tests := []struct {
+		name string
+		args args
+		want []string
+	}{
+		{
+			"test1",
+			args{"HOW ARE YOU"},
+			[]string{"HAY", "ORO", "WEU"},
+		},
+		{
+			"test2",
+			args{"TO BE OR NOT TO BE"},
+			[]string{"TBONTB", "OEROOE", "   T"},
+		},
+		{
+			"test3",
+			args{"CONTEST IS COMING"},
+			[]string{"CIC", "OSO", "N M", "T I", "E N", "S G", "T"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := transform(tt.args.s); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("transform() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}