#include<stdio.h>
int p[1003];
int ans[1000006], aa;
int main()
{
	int n, k;
	scanf("%d %d", &n, &k);
	int i;
	for (i = 0; i < n; i++)
		scanf("%d", &p[i]);
	aa = 0;
	for (i = 0; i + k < n; i++)
	{
		if (p[i] > p[i + k])
		{
			ans[aa++] = i + 1;
			p[i] ^= p[i + k];
			p[i + k] ^= p[i];
			p[i] ^= p[i + k];
			i -= k + 1;
		}
	}
	for (i = 0; i < n - 1; i++)
		if (p[i] > p[i + 1])
			aa = -1;
	printf("%d\n", aa);
	for (i = 0; i < aa; i++)
		printf("%d %d\n", ans[i], ans[i] + k);
	return 0;
}