diff --git a/go.mod b/go.mod
index e9ce053..002b262 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,3 @@
 module structs
 
-go 1.21.0
+go 1.21.1
diff --git a/main.go b/main.go
index af1ae19..b46572c 100644
--- a/main.go
+++ b/main.go
@@ -1,5 +1,10 @@
 package main
 
+import (
+	"fmt"
+	"structs/zoo"
+)
+
 /*
 0. Declaration
 1. Different types
@@ -19,7 +24,19 @@ package main
 16. Assignment
 */
 
+func main() {
 
+	cage1 := zoo.Cage{Size: "10x10", Color: "green", Number: 1, Animal: zoo.Animal{Kind: "Leon", Name: "Pusic", Number_of_legs: 4, Predator: true}}
+	cages := []zoo.Cage{cage1, {Size: "20x20", Color: "red", Number: 2, Animal: zoo.Animal{Kind: "mouse", Name: "Miki", Number_of_legs: 4, Predator: false}}}
+
+	leon := zoo.Animal{Kind: "Elephant", Name: "White", Number_of_legs: 4, Predator: false}
+	cages = append(cages, zoo.Cage{Size: "10x10", Color: "green", Number: 1, Animal: leon})
+
+	fmt.Printf("On duty today: %s, with %d years of experience\n", zoo.Mihalich.Name, zoo.Mihalich.Experience)
+	fmt.Printf("We have a %v cages\n", len(cages))
+	for i := 0; i < len(cages); i++ {
+		fmt.Printf("In cage: %v cages, we have %s, named %s. And ", i+1, cages[i].Animal.Kind, cages[i].Animal.Name)
+		cages[i].Animal.Food()
+	}
 
-func main() {
 }
diff --git a/structs/0_declaration.go b/structs/0_declaration.go
index ff09605..623a334 100644
--- a/structs/0_declaration.go
+++ b/structs/0_declaration.go
@@ -8,6 +8,13 @@ type user struct {
 	Age     int
 }
 
+type User struct {
+	// Contains different field names with different types
+	Name    string
+	Surname string
+	Age     int
+}
+
 // Public struct
 type Post struct {
 	// Public field
diff --git a/zoo/zoo.go b/zoo/zoo.go
new file mode 100644
index 0000000..d3a33df
--- /dev/null
+++ b/zoo/zoo.go
@@ -0,0 +1,35 @@
+package zoo
+
+// Private struct, visible inside this package only
+type zookeeper struct {
+	// Contains different field names with different types
+	Name       string
+	Surname    string
+	Age        int
+	Experience int
+}
+
+type Animal struct {
+	Kind           string
+	Name           string
+	Number_of_legs int
+	Predator       bool
+}
+
+type Cage struct {
+	Size   string
+	Color  string
+	Number int
+	Animal Animal
+}
+
+func (a *Animal) Food() {
+	if a.Predator == true {
+		println("it likes meat")
+	} else {
+		println("it likes apple")
+	}
+
+}
+
+var Mihalich = zookeeper{"Mihail", "Ivanov", 56, 30}