use std::collections::HashMap;

fn main() {
    let mut map = HashMap::new();

    map.insert("a", 1);
    map.insert("b", 2);
    map.insert("c", 3);

    for val in map.values_mut() {
        *val += 10;
    }

    for (key, val) in map {
        println!("{} {}", key, val);
    }
}