#include <bits/stdc++.h>
using namespace std;
int sx = 1, sy = 1, n = 0, m = 0;
void next() {
  cout << sx << " " << sy << " ";
  if (sx % 2 == 1) {
    if (sy < m) {
      sy++;
    } else {
      sx++;
    }
  } else {
    if (sy > 1) {
      sy--;
    } else {
      sx++;
    }
  }
}
int main(void) {
  int i, j, k, r;
  cin >> n >> m >> k;
  for (i = 0; i < k - 1; i++) {
    cout << 2 << " ";
    next();
    next();
    cout << "\n";
  }
  cout << (m * n - 2 * (k - 1)) << " ";
  for (i = 0; i < m * n - 2 * (k - 1); i++) {
    next();
  }
  return 0;
}
