#include <bits/stdc++.h>
using namespace std;
int n, m, k;
int per;
int main() {
  cin >> n >> m >> k;
  per = 2;
  int flag = 0;
  int sum = 0;
  int ff = 0;
  int a = 1;
  for (int i = 1; i <= n; ++i) {
    if (!flag) {
      for (int j = 1; j <= m; ++j) {
        if (sum % 2 == 0 && a == k) {
          if (ff++) cout << endl;
          cout << n * m - 2 * (k - 1);
          a++;
        }
        if (sum % 2 == 0 && a < k) {
          if (ff++) cout << endl;
          cout << "2";
          a++;
        }
        cout << " " << i << " " << j;
        sum++;
      }
      flag = 1;
      continue;
    }
    if (flag) {
      for (int j = m; j >= 1; --j) {
        if (sum % 2 == 0 && a == k) {
          if (ff++) cout << endl;
          cout << n * m - 2 * (k - 1);
          a++;
        }
        if (sum % 2 == 0 && a < k) {
          if (ff++) cout << endl;
          cout << "2";
          a++;
        }
        cout << " " << i << " " << j;
        sum++;
      }
      flag = 0;
      continue;
    }
  }
}
