Not-upgradable Solana Program

// Short way to check if prime
fn is_prime(x: i64) -> bool {
    let last = (x as f64).sqrt() as i64 + 1;
    x > 1 && (2..last).all(|d| x % d != 0)
}

fn is_valid(s: String) -> bool {
    let mut stack = Vec::new();
    for i in s.chars() {
        match i {
            '{' => stack.push('}'),
            '(' => stack.push(')'),
            '[' => stack.push(']'),
            '}'|')'|']' if Some(i) != stack.pop() => return false,
            _ => (),
        }
    }   
    return stack.is_empty();
}
  
fn main() {

println!("{}", is_valid("()[]{}".to_string()) )

}

// rgb to hex conversion
fn rgb(r: i32, g: i32, b: i32) -> String {
    format!("{:02X}{:02X}{:02X}", 
        r as f32 as u8, 
        g as f32 as u8, 
        b as f32 as u8) 
}

fn main() {
    let (r, g, b) = (123, 86, 200);
    println!("rgb {} {} {} to hex {} ", r, g, b, rgb(r, g, b));
}

use solana_program::{
    account_info:: AccountInfo, entrypoint, entrypoint::ProgramResult, msg, pubkey::Pubkey,

};

entrypoint!(process_instructions);
fn process_instructions(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8],
) -> ProgramResult{

    msg!("Program id: {}, accounts: {}, instructions: {:?}",
        program_id,
        accounts.len(),
        instruction_data
    );

    Ok(())
}

[dependencies]
	solana-program = "=1.10.2"
[lib]
	crate-type = ["cdylib", "lib"]

use solana_program::{
    account_info::AccountInfo, entrypoint, entrypoint::ProgramResult, msg, pubkey::Pubkey,

};

entrypoint!(process_instruction);

fn process_instruction(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8],
) -> ProgramResult{

    let (key, rem) = instruction_data.split_first().unwrap();
    
    let value: u64=rem
        .get(0..8)        
        .and_then(|slice|slice.try_into().ok())
        .map(u64::from_le_bytes)
        .unwrap_or(0);
    msg!("value {:?}:", value);
    msg!("El ingrediente secreto de mi sopa de ingrediente secreto es... nada");
    msg!("Program id: {}, accounts: {}, instructions: {:?}",
        program_id,
        accounts.len(),
        instruction_data
    );

    Ok(())
}