use proconio::input;

fn main() {
    input! {
        _n: usize,
        m: usize,
        a_vec: [u64; m],
    }

    let mut ans = vec!((a_vec[0], 1));

    for i in 0..m - 1 {
        if a_vec[i + 1] == a_vec[i] + 1 {
            let (s, l) = ans.last().unwrap().clone();
            let length = ans.len();
            ans[length - 1] = (s, l + 1);
        } else {
            ans.push((a_vec[i + 1], 1));
        }
    }

    println!("{}", ans.len());

    for (s, l) in ans {
        println!("{} {}", s, l);
    }
}