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