#include <bits/stdc++.h>
using namespace std;
int x = 1, y = 1, n, m, k, flag = 0;
void printme() {
  cout << x << " " << y << " ";
  if (y == m && flag == 0) {
    x++;
    flag = 1;
    y++;
  } else if (y == 1 && flag == 1) {
    x++;
    flag = 0;
    y--;
  }
  if (flag == 0)
    y++;
  else
    y--;
}
int main() {
  cin >> n >> m >> k;
  int x = n * m - 2 * (k - 1);
  while (k > 1) {
    cout << "2 ";
    printme();
    printme();
    cout << endl;
    k--;
  }
  cout << x << " ";
  while (x--) printme();
  return 0;
}
