#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e4 + 5;
const int M = 1e9 + 7;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int n, m, k;
  cin >> n >> m >> k;
  int loc = n * m;
  int x = loc / k, y = loc % k;
  int i = 1, j = 1;
  bool turn = true;
  for (int it = 0; it < y; it++) {
    int cnt = x + 1;
    cout << cnt << " ";
    while (cnt--) {
      cout << i << " " << j << " ";
      if (turn)
        i++;
      else
        i--;
      if (i == n + 1)
        turn = !turn, i = n, j++;
      else if (i == 0)
        i = 1, turn = !turn, j++;
    }
    cout << "\n";
  }
  for (int it = 0; it < k - y; it++) {
    int cnt = x;
    cout << cnt << " ";
    while (cnt--) {
      cout << i << " " << j << " ";
      if (turn)
        i++;
      else
        i--;
      if (i == n + 1)
        turn = !turn, i = n, j++;
      else if (i == 0)
        i = 1, turn = !turn, j++;
    }
    cout << "\n";
  }
  return 0;
}
