#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < b; i++)
using ll = long long;

int main(){
	int n, m;
	cin >> n >> m;
	vector<int> a(m);
	rep(i, 0, m) cin >> a[i];
	using P = pair<int, int>;
	vector<P> p;
	rep(i, 0, m) {
		int j = i;
		while(j + 1 < m && a[j] + 1 == a[j + 1]) j++;
		p.emplace_back(a[i], j - i + 1);
		i = j;
	}
	int x = p.size();
	cout << x << endl;
	rep(i, 0, x) cout << p[i].first << " " << p[i].second << endl;
}