use itertools::Itertools;
use proconio::input;

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

    let mut ans = vec![];
    let mut start_num = a[0];
    let mut cnt = 1;
    for &a_i in a.iter().skip(1) {
        if a_i != start_num + cnt {
            ans.push((start_num, cnt));
            start_num = a_i;
            cnt = 1;
            continue;
        }
        cnt += 1;
    }
    ans.push((start_num, cnt));

    println!("{}", ans.len());
    println!(
        "{}",
        ans.iter()
            .map(|&(num, cnt)| format!("{} {}", num, cnt))
            .join("\n")
    );
}