#include <bits/stdc++.h>
using namespace std;
const int N = 101;
int a[4], ans;
string s;
int main() {
  int n, m, k, y = 1, x = 1, a;
  bool f = 0;
  cin >> n >> m >> k;
  for (int i = 0; i < k - 1; i++) {
    a = 2;
    cout << a << " ";
    while (a--) {
      if (y > m && !f) {
        f = !f;
        x++, y = m;
      } else if (y == 0 && f) {
        f = !f;
        x++, y = 1;
      }
      if (!f)
        cout << x << " " << y++ << " ";
      else
        cout << x << " " << y-- << " ";
    }
    cout << "\n";
  }
  a = n * m - 2 * (k - 1);
  cout << a << " ";
  while (a--) {
    if (y > m && !f) {
      f = !f;
      x++, y = m;
    } else if (y == 0 && f) {
      f = !f;
      x++, y = 1;
    }
    if (!f)
      cout << x << " " << y++ << " ";
    else
      cout << x << " " << y-- << " ";
  }
  return 0;
}
