#include <bits/stdc++.h>
using namespace std;
int n, m, x, y, k[2], cnt[51], f[51][51], ans[2][100001][4];
struct rua {
  int x, y, id;
} a[51];
bool cmp(rua p, rua q) { return p.x < q.x; }
void move(int i, int j, int dx, int dy) {
  if (f[a[i].x + dx][a[i].y + dy]) move(f[a[i].x + dx][a[i].y + dy], j, dx, dy);
  ans[j][++k[j]][0 + j * 2] = a[i].x, ans[j][k[j]][1 + j * 2] = a[i].y;
  ans[j][k[j]][2 - j * 2] = a[i].x + dx, ans[j][k[j]][3 - j * 2] = a[i].y + dy;
  swap(f[a[i].x][a[i].y], f[a[i].x + dx][a[i].y + dy]);
  a[i].x += dx, a[i].y += dy;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int j = 0; j < 2; j++) {
    for (int i = 1; i <= m; i++) scanf("%d%d", &a[i].x, &a[i].y), a[i].id = i;
    sort(a + 1, a + m + 1, cmp);
    memset(f, 0, sizeof(f));
    for (int i = 1; i <= m; i++) f[a[i].x][a[i].y] = i;
    for (int i = 1; i <= m; i++) {
      while (a[i].x < i) move(i, j, 1, 0);
      while (a[i].x > i) move(i, j, -1, 0);
    }
    for (int i = 1; i <= m; i++) {
      while (a[i].y < a[i].id) move(i, j, 0, 1);
      while (a[i].y > a[i].id) move(i, j, 0, -1);
    }
    for (int i = 1; i <= m; i++) {
      while (a[i].x < a[i].id) move(i, j, 1, 0);
      while (a[i].x > a[i].id) move(i, j, -1, 0);
    }
  }
  printf("%d\n", k[0] + k[1]);
  for (int i = 1; i <= k[0]; i++)
    for (int j = 0; j < 4; j++)
      printf("%d%c", ans[0][i][j], j < 3 ? ' ' : '\n');
  for (int i = k[1]; i >= 1; i--)
    for (int j = 0; j < 4; j++)
      printf("%d%c", ans[1][i][j], j < 3 ? ' ' : '\n');
  return 0;
}
