Rust code shared from the playground

playground.rs

const _INPUT: usize = 3;
const INPUT: usize = 369;

fn main() {
    let mut after_0 = None;
    let mut pos = 0;
    let mut buffer_len = 1;
    
    for new_val in 1..50000001 {
        pos = (pos + INPUT) % buffer_len;
        if pos == 0 {
            after_0 = Some(new_val);
        }
        buffer_len += 1;
        pos += 1;
    }
    
    println!("{}", after_0.unwrap());
}