use proconio::{fastout, input};

#[fastout]
fn main() {
    input! {
        _n: usize,
        m: usize,
        a: [u32; m],
    }
    println!("{}", output(solve(m, a)));
}

fn solve(m: usize, a: Vec<u32>) -> Vec<(u32, u32)> {
    let mut ans = Vec::with_capacity(m);
    for a in a {
        if let Some((s, l)) = ans.last_mut() {
            if a == *s + *l {
                *l += 1;
            } else {
                ans.push((a, 1));
            }
        } else {
            ans.push((a, 1));
        }
    }
    ans
}

fn output(ans: Vec<(u32, u32)>) -> String {
    ans.len().to_string()
        + "\n"
        + &ans
            .into_iter()
            .map(|(s, l)| s.to_string() + " " + &l.to_string())
            .collect::<Vec<_>>()
            .join("\n")
}