#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const int FFTMOD = 119 << 23 | 1;
const int INF = (int)1e9 + 23111992;
const long long LINF = (long long)1e18 + 23111992;
const long double PI = acos((long double)-1);
const long double EPS = 1e-9;
inline long long gcd(long long a, long long b) {
  long long r;
  while (b) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
inline long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
inline long long fpow(long long n, long long k, int p = MOD) {
  long long r = 1;
  for (; k; k >>= 1) {
    if (k & 1) r = r * n % p;
    n = n * n % p;
  }
  return r;
}
template <class T>
inline int chkmin(T& a, const T& val) {
  return val < a ? a = val, 1 : 0;
}
template <class T>
inline int chkmax(T& a, const T& val) {
  return a < val ? a = val, 1 : 0;
}
inline long long isqrt(long long k) {
  long long r = sqrt(k) + 1;
  while (r * r > k) r--;
  return r;
}
inline long long icbrt(long long k) {
  long long r = cbrt(k) + 1;
  while (r * r * r > k) r--;
  return r;
}
inline void addmod(int& a, int val, int p = MOD) {
  if ((a = (a + val)) >= p) a -= p;
}
inline void submod(int& a, int val, int p = MOD) {
  if ((a = (a - val)) < 0) a += p;
}
inline int mult(int a, int b, int p = MOD) { return (long long)a * b % p; }
inline int inv(int a, int p = MOD) { return fpow(a, p - 2, p); }
inline int sign(long double x) { return x < -EPS ? -1 : x > +EPS; }
inline int sign(long double x, long double y) { return sign(x - y); }
const int maxn = 50 + 5;
int n, m;
int x[maxn];
int y[maxn];
int z[maxn];
int t[maxn];
int f[maxn][maxn];
int g[maxn][maxn];
int fromx[maxn][maxn];
int fromy[maxn][maxn];
int vis[maxn][maxn];
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
int inside(int u, int v) {
  if (!(0 <= u && u < n)) return 0;
  if (!(0 <= v && v < n)) return 0;
  return 1;
}
vector<pair<pair<int, int>, pair<int, int> > > go(int x, int y, int z, int t) {
  memset(vis, 0, sizeof(vis));
  queue<int> que;
  vis[x][y] = 1, que.push(x), que.push(y);
  while (int((que).size())) {
    int u = que.front();
    que.pop();
    int v = que.front();
    que.pop();
    for (int i = (0); i < (4); ++i) {
      int nu = u + dx[i];
      int nv = v + dy[i];
      if (inside(nu, nv) && !vis[nu][nv] && !f[nu][nv]) {
        fromx[nu][nv] = u;
        fromy[nu][nv] = v;
        vis[nu][nv] = 1, que.push(nu), que.push(nv);
      }
    }
  }
  assert(vis[z][t]);
  swap(f[x][y], f[z][t]);
  vector<pair<pair<int, int>, pair<int, int> > > res;
  while (make_pair(z, t) != make_pair(x, y)) {
    int nz = fromx[z][t];
    int nt = fromy[z][t];
    res.push_back(make_pair(make_pair(nz, nt), make_pair(z, t)));
    z = nz, t = nt;
  }
  reverse((res).begin(), (res).end());
  return res;
}
void volamtruyenkyii() {
  cin >> n >> m;
  for (int i = (0); i < (m); ++i)
    cin >> x[i] >> y[i], x[i]--, y[i]--, f[x[i]][y[i]] = i + 1;
  for (int i = (0); i < (m); ++i)
    cin >> z[i] >> t[i], z[i]--, t[i]--, g[z[i]][t[i]] = i + 1;
  if (n == 1) {
    cout << 0 << "\n";
    return;
  }
  vector<pair<pair<int, int>, pair<int, int> > > res;
  for (int i = (0); i < (n); ++i)
    for (int j = (0); j < (n); ++j)
      if (f[i][j]) {
        int k = f[i][j] - 1;
        int ptr = i;
        while (ptr && !f[ptr - 1][j]) ptr--;
        auto vals = go(x[k], y[k], ptr, j);
        res.insert(res.end(), (vals).begin(), (vals).end());
        x[k] = ptr, y[k] = j;
      }
  for (int i = (n)-1; i >= (1); --i)
    for (int j = (0); j < (n); ++j)
      if (f[i][j]) {
        int k = f[i][j] - 1;
        for (int l = (0); l < (n); ++l)
          if (!f[0][l]) {
            auto vals = go(x[k], y[k], 0, l);
            res.insert(res.end(), (vals).begin(), (vals).end());
            x[k] = 0, y[k] = l;
            break;
          }
      }
  vector<int> ver;
  for (int i = (0); i < (m); ++i) ver.push_back(i);
  sort((ver).begin(), (ver).end(), [&](int i, int j) {
    if (t[i] != t[j]) return t[i] < t[j];
    return i < j;
  });
  int ptr = 0;
  for (int i : ver) {
    auto vals = go(x[i], y[i], n - 1, ptr);
    res.insert(res.end(), (vals).begin(), (vals).end());
    x[i] = n - 1, y[i] = ptr++;
  }
  for (int i = (0); i < (n); ++i) {
    vector<int> vals;
    for (int j = (0); j < (n); ++j)
      if (g[i][j]) {
        vals.push_back(g[i][j] - 1);
      }
    if (i >= n - 2) {
      for (int j = (0); j < (int((vals).size())); ++j) {
        int k = vals[j];
        auto val = go(x[k], y[k], i, j);
        res.insert(res.end(), (val).begin(), (val).end());
        x[k] = i, y[k] = j;
      }
    }
    for (int j = (int((vals).size())) - 1; j >= (0); --j) {
      int k = vals[j];
      auto val = go(x[k], y[k], z[k], t[k]);
      res.insert(res.end(), (val).begin(), (val).end());
    }
  }
  cout << int((res).size()) << "\n";
  for (auto it : res) {
    cout << it.first.first + 1 << " " << it.first.second + 1 << " "
         << it.second.first + 1 << " " << it.second.second + 1 << "\n";
  }
}
int main(int argc, char* argv[]) {
  ios_base::sync_with_stdio(0), cin.tie(0);
  if (argc > 1) {
  }
  if (argc > 2) {
    assert(freopen(argv[2], "wb", stdout));
  }
  volamtruyenkyii();
  cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
  return 0;
}
