#include<stdio.h>
int a[200005];
int ans[200005][2], aa;
int main()
{
	int n, m;
	scanf("%d %d", &n, &m);
	int i, j;
	for (i = 0; i < m; i++)
		scanf("%d", &a[i]);
	aa = 0;
	a[m] = -1;
	for (i = 0; i < m; i = j)
	{
		for (j = i; j - i == a[j] - a[i]; j++);
		ans[aa][0] = a[i];
		ans[aa++][1] = j - i;
	}
	printf("%d\n", aa);
	for (i = 0; i < aa; i++)
		printf("%d %d\n", ans[i][0], ans[i][1]);
	return 0;
}