use std::collections::HashMap;
use std::hash::{Hash, Hasher};
use std::fmt;
 
#[derive(Debug)]
struct Person {
    name: String,
    age: u8,
}
 
impl PartialEq for Person {
    fn eq(&self, other: &Self) -> bool {
        self.name == other.name && self.age == other.age
    }
}
 
impl Eq for Person {}
 
impl Hash for Person {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.name.hash(state);
        self.age.hash(state);
    }
}
 
impl fmt::Display for Person {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{} ({})", self.name, self.age)
    }
}
 
fn main() {
    let mut people: HashMap<Person, &str> = HashMap::new();
    
    let alice = Person { name: String::from("Alice"), age: 30 };
    let bob = Person { name: String::from("Bob"), age: 25 };
    
    people.insert(alice, "Engineer");
    people.insert(bob, "Designer");
    
    let lookup = Person { name: String::from("Alice"), age: 30 };
    if let Some(&profession) = people.get(&lookup) {
        println!("Alice is an {}", profession);
    }
    
    println!("Total people: {}", people.len());
}