Counterexample

main.rs

use std::process::exit;

fn main() {
    
    // The minimum values of m to search though
    let m_min = 2;
    let m_max = 16;

    for m in m_min..m_max {
        print!("For {}:", m);

        let m2 = m * m;

        // Consider a in [0, m]
        for a in 0..m {

            // Create b from a + multiples of m^2, to only generate values of b that are congruent
            // with b mod m
            for i in 0..100 {
                let b = a + i * m2;

                println!("  {} ≡ {} (mod {}^2)", a, b, m);
                if a % m == b % m {
                    println!("      {} ≡ {} (mod {})", a, b, m)
                } else {

                    // We've found a counterexample, end early!
                    println!("      {} ≡ {} (mod {}) == FALSE!", a, b, m);
                    exit(0);
                }
                

            }
        };

    }


}