#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, M, N, k, p, s, t;
  cin >> N >> M >> k;
  s = 0;
  t = N * M - 2 * (k - 1);
  for (j = 1; j <= M; j++) {
    p = 1 - 2 * ((j - 1) % 2);
    for (i = 1; i <= N; i++) {
      if (k > 1 && s % 2 == 0)
        cout << 2;
      else if (k == 1)
        cout << t;
      cout << " " << p * i + (N + 1) * ((j - 1) % 2) << " " << j;
      s++;
      if (k > 1) {
        if (s % 2 == 0) {
          cout << endl;
          k--;
        }
      } else
        k--;
    }
  }
  return 0;
}
