Shared via Rust Playground

playground.rs

// open.rs
use std::error::Error;
use std::fs::File;
use std::io::prelude::*;
use std::path::Path;
use std::char;

fn main() {
    let a = 'a' as u32;
    let outer = 25;
    let inner = 25;
    for i in 0..outer {
        for j in 0..inner {
            print!("AAA{}{}BBB", char::from_u32(i+a).unwrap(), char::from_u32(j+a).unwrap());
        }
    }
}