#include <bits/stdc++.h>
using namespace std;
template <class T>
T Abs(T x) {
  return x < 0 ? -x : x;
}
int N, M, K;
int main() {
  while (cin >> N >> M >> K) {
    int i = 0;
    int j = -1;
    for (int t = (int)0, _m = (int)K - 1; t < _m; ++t) {
      cout << 2;
      for (int my = (int)0, _m = (int)2; my < _m; ++my) {
        int yDir;
        if (i % 2 == 0)
          yDir = 1;
        else
          yDir = -1;
        j += yDir;
        bool addrow = false;
        if (j < 0) {
          j = 0;
          addrow = true;
        } else if (j == M) {
          j = M - 1;
          addrow = true;
        }
        if (addrow) i++;
        cout << " " << i + 1 << " " << j + 1;
      }
      cout << endl;
    }
    int cnt = N * M - 2 * (K - 1);
    cout << cnt;
    for (int my = (int)0, _m = (int)cnt; my < _m; ++my) {
      int yDir;
      if (i % 2 == 0)
        yDir = 1;
      else
        yDir = -1;
      j += yDir;
      bool addrow = false;
      if (j < 0) {
        j = 0;
        addrow = true;
      } else if (j == M) {
        j = M - 1;
        addrow = true;
      }
      if (addrow) i++;
      cout << " " << i + 1 << " " << j + 1;
    }
    cout << endl;
  }
}
