#include <bits/stdc++.h>
using namespace std;
const double infd = 1e+9, pi = M_PI;
const int infi = INT_MAX;
template <class T>
inline T sqr(T x) {
  return x * x;
}
int n, m;
int x, y;
void next() {
  if (x % 2 == 1) {
    if (y == m)
      x++;
    else
      y++;
  } else {
    if (y == 1)
      x++;
    else
      y--;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  int k;
  cin >> n >> m >> k;
  int twoTr = k - 1;
  int lastLen = n * m - twoTr * 2;
  if (lastLen == 1) twoTr--, lastLen = 3;
  x = 1, y = 1;
  for (int i = 0; i < twoTr; i++) {
    cout << "2 ";
    for (int j = 0; j < 2; j++) {
      cout << x << ' ' << y << ' ';
      next();
    }
    cout << endl;
  }
  cout << lastLen << ' ';
  for (int i = 0; i < lastLen; i++) {
    cout << x << ' ' << y << ' ';
    next();
  }
  cout << endl;
  return 0;
}
