error[E0596]: cannot borrow data in a `&` reference as mutable
  --> src/main.rs:72:13
   |
72 |             income_list.push( 1);
   |             ^^^^^^^^^^^ cannot borrow as mutable

lazy_static! {
    static ref expense_list: Vec<i64> = Vec::new();
    static ref  income_list: Vec<u64> = Vec::new();
}

let mut income_input = String::new();
io::stdin().read_line(&mut income_input);
let mut income_input: u64 = match income_input.trim().parse() {
                Ok(num) => num,
                Err(_) => break,
                };
income_list.push(1); // it was income_list.push(income_input)