#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  vector<vector<int>> v;
  vector<int> cur;
  if ((n * m) % k == 0) {
    int div = (n * m) / k;
    for (int i = 0; i < n; i++) {
      if (!(i & 1)) {
        for (int j = 0; j < m; j++) {
          cur.push_back(i + 1);
          cur.push_back(j + 1);
          if (cur.size() >= div * 2) {
            vector<int> add = cur;
            v.push_back(add);
            cur.clear();
          }
        }
      } else {
        for (int j = m - 1; j >= 0; j--) {
          if (cur.size() <= div * 2) {
            cur.push_back(i + 1);
            cur.push_back(j + 1);
          }
          if (cur.size() >= div * 2) {
            vector<int> add = cur;
            v.push_back(add);
            cur.clear();
          }
        }
      }
    }
  } else {
    int div = ((n * m) - 2) / (k - 1);
    int count = 0;
    int flag = 0;
    for (int i = 0; i < n; i++) {
      if (!(i & 1)) {
        for (int j = 0; j < m; j++) {
          if (count == k - 1 && flag == 0) {
            div = (n * m - (k - 1) * (div));
            flag = 1;
          }
          cur.push_back(i + 1);
          cur.push_back(j + 1);
          if (cur.size() >= div * 2) {
            vector<int> add = cur;
            v.push_back(add);
            cur.clear();
            count++;
          }
        }
      } else {
        for (int j = m - 1; j >= 0; j--) {
          if (count == k - 1 && flag == 0) {
            div = (n * m - (k - 1) * (div));
            flag = 1;
          }
          if (cur.size() <= div * 2) {
            cur.push_back(i + 1);
            cur.push_back(j + 1);
          }
          if (cur.size() >= div * 2) {
            vector<int> add = cur;
            v.push_back(add);
            cur.clear();
            count++;
          }
        }
      }
    }
  }
  for (int i = 0; i < v.size(); i++) {
    int s = v[i].size();
    s /= 2;
    cout << s << " ";
    for (int j = 0; j < v[i].size(); j++) {
      cout << v[i][j] << " ";
    }
    cout << endl;
  }
  return 0;
}
