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