use proconio::input;

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

    if m == 1 {
        println!("{} 1", a[0]);
        return;
    }

    let mut prev = a[0];
    let mut seq_count = 1;
    let mut seq_start = a[0];
    let mut ans = vec![];
    for i in 1..m {
        if a[i] == prev + 1 {
            seq_count += 1;
        } else {
            ans.push((seq_start, seq_count));
            seq_count = 1;
            seq_start = a[i];
        }
        prev = a[i];
    }
    ans.push((seq_start, seq_count));

    println!("{}", ans.len());
    for (i, j) in ans {
        println!("{} {}", i, j);
    }
}