/* -*- coding: utf-8 -*-
 *
 * 3324.cc:  No.3324 繝上う繝ｩ繧､繝亥虚逕ｻ - yukicoder
 */

#include<cstdio>
#include<vector>
#include<algorithm>
#include<utility>

using namespace std;

/* constant */

const int MAX_M = 200000;

/* typedef */

using pii = pair<int,int>;
using vpii = vector<pii>;

/* global variables */

int as[MAX_M];

/* subroutines */

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < m; i++) scanf("%d", as + i);

  vpii fs;
  for (int i = 0; i < m;) {
    int j = i++;
    while (i < n && as[i - 1] + 1 == as[i]) i++;
    fs.push_back({as[j], i - j});
  }

  printf("%d\n", (int)fs.size());
  for (auto [si, li]: fs) printf("%d %d\n", si, li);

  return 0;
}