diff --git a/Cargo.toml b/Cargo.toml
index 3fcda58..1b8b9cf 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,3 +4,6 @@ version = "0.1.0"
 authors = ["Tsuyoshi Maeda <oasis5tsuyoshi@gmail.com>"]
 
 [dependencies]
+serde = "1.0.23"
+serde_derive = "1.0.23"
+serde_json = "1.0.7"
\ No newline at end of file
diff --git a/src/helpers/math.rs b/src/helpers/math.rs
new file mode 100644
index 0000000..075b3f9
--- /dev/null
+++ b/src/helpers/math.rs
@@ -0,0 +1,13 @@
+pub fn add(a: i32, b: i32) -> i32 {
+  a + b
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn it_add() {
+    assert_eq!(1 + 2, add(1, 2));
+  }
+}
\ No newline at end of file
diff --git a/src/helpers/mod.rs b/src/helpers/mod.rs
new file mode 100644
index 0000000..019ce55
--- /dev/null
+++ b/src/helpers/mod.rs
@@ -0,0 +1,2 @@
+pub mod math;
+pub mod output;
\ No newline at end of file
diff --git a/src/helpers/output.rs b/src/helpers/output.rs
new file mode 100644
index 0000000..2081035
--- /dev/null
+++ b/src/helpers/output.rs
@@ -0,0 +1,15 @@
+pub fn string(input: &str) -> () {
+  println!("{}", input);
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn it_output_string() {
+    // Expected no error.
+    string("abc");
+    assert!(true);
+  }
+}
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
index 31e1bb2..e774833 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,4 @@
-#[cfg(test)]
-mod tests {
-    #[test]
-    fn it_works() {
-        assert_eq!(2 + 2, 4);
-    }
-}
+#[macro_use] extern crate serde_derive;
+
+pub mod helpers;
+pub mod models;
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 218a5fb..5700cde 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,4 +1,13 @@
+extern crate cc2_rust_workshop;
+extern crate serde_json;
+
+use cc2_rust_workshop::models::person::{Person};
+use cc2_rust_workshop::helpers::math;
+use cc2_rust_workshop::helpers::output;
+
 fn main() {
+  // Basic requirement parts.
+
   let number_1 = 1;
   println!("{}", number_1);
 
@@ -6,10 +15,10 @@ fn main() {
   number_2 += 1;
   println!("{}", number_2);
 
-  let number_3 = add(1, 2);
+  let number_3 = math::add(1, 2);
   println!("{}", number_3);
 
-  output_string("this is input value");
+  output::string("this is input value");
 
   let person = Person::new(
     "Code",
@@ -18,63 +27,29 @@ fn main() {
   );
   println!("{:?}", person);
   person.greet();
-}
-
-fn add(a: i32, b: i32) -> i32 {
-  a + b
-}
-#[test]
-fn it_add() {
-  assert_eq!(1 + 2, add(1, 2));
-}
 
-fn output_string(input: &str) -> () {
-  println!("{}", input);
-}
-#[test]
-fn it_output_string() {
-  // Expected no error.
-  output_string("abc");
-  assert!(true);
-}
+  // Advanced requirements parts.
 
-#[derive(Debug)]
-struct Person {
-  first_name: String,
-  last_name: String,
-  age: u8
-}
+  // Convert the Point to a JSON string.
+  let serialized_person = serde_json::to_string(&person).unwrap();
+  println!("serialized_person = {}", serialized_person);
 
-impl Person {
-  fn new(first_name: &str, last_name: &str, age: u8) -> Person {
-    Person {
-      first_name: first_name.to_string(),
-      last_name: last_name.to_string(),
-      age: age
-    }
-  }
+  // Convert the JSON string back to a Person.
+  let deserialized_person: Person = serde_json::from_str(&serialized_person).unwrap();
+  println!("deserialized_person = {:?}", deserialized_person);
 
-  fn greet(&self) -> () {
-    println!(
-      "My name is {} {}. I'm {} years old.",
-      &self.first_name,
-      &self.last_name,
-      &self.age
+  let mut persons: Vec<Person> = vec![];
+  for i in 0..5 {
+    let person = Person::new(
+      &format!("FN_{}", i),
+      &format!("LN_{}", i),
+      i
     );
+    persons.push(person);
+  }
+  println!("{}", persons.len());
+  for p in persons {
+    // If you use {:#?} instead of {:?}, the format becomes more readable.
+    println!("{:#?}", p);
   }
-}
-#[test]
-fn it_person() {
-  let person = Person::new("FN", "LN", 1);
-  assert_eq!("FN", person.first_name);
-  assert_eq!("LN", person.last_name);
-  assert_eq!(1, person.age);
-}
-#[test]
-fn it_person_greet() {
-  let person = Person::new("FN", "LN", 1);
-
-  // Expected no error.
-  person.greet();
-  assert!(true);
 }
\ No newline at end of file
diff --git a/src/models/mod.rs b/src/models/mod.rs
new file mode 100644
index 0000000..c61d2e3
--- /dev/null
+++ b/src/models/mod.rs
@@ -0,0 +1 @@
+pub mod person;
\ No newline at end of file
diff --git a/src/models/person.rs b/src/models/person.rs
new file mode 100644
index 0000000..8f324eb
--- /dev/null
+++ b/src/models/person.rs
@@ -0,0 +1,46 @@
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Person {
+  first_name: String,
+  last_name: String,
+  age: u8
+}
+
+impl Person {
+  pub fn new(first_name: &str, last_name: &str, age: u8) -> Person {
+    Person {
+      first_name: first_name.to_string(),
+      last_name: last_name.to_string(),
+      age: age
+    }
+  }
+
+  pub fn greet(&self) -> () {
+    println!(
+      "My name is {} {}. I'm {} years old.",
+      &self.first_name,
+      &self.last_name,
+      &self.age
+    );
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn it_person() {
+    let person = Person::new("FN", "LN", 1);
+    assert_eq!("FN", person.first_name);
+    assert_eq!("LN", person.last_name);
+    assert_eq!(1, person.age);
+  }
+  #[test]
+  fn it_person_greet() {
+    let person = Person::new("FN", "LN", 1);
+
+    // Expected no error.
+    person.greet();
+    assert!(true);
+  }
+}
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