#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, m, k;
  cin >> n >> m >> k;
  long long t = k;
  long long c = 0;
  long long x = 1, y = 1;
  for (long long i = 1; i <= n; i++) {
    if (i % 2) {
      for (long long j = 1; j <= m; j++) {
        if (k == 1) {
          x = i;
          y = j;
          j = m;
          i = n;
          break;
        }
        if (c == 0) cout << "2 ";
        cout << i << " " << j << " ";
        c++;
        if (c == 2) {
          k--;
          c = 0;
          cout << "\n";
        }
      }
    } else {
      for (long long j = m; j >= 1; j--) {
        if (k == 1) {
          x = i;
          y = j;
          j = m;
          i = n;
          break;
        }
        if (c == 0) cout << "2 ";
        cout << i << " " << j << " ";
        c++;
        if (c == 2) {
          k--;
          c = 0;
          cout << "\n";
        }
      }
    }
  }
  cout << n * m - 2 * (t - 1) << " ";
  for (long long i = x; i <= n; i++) {
    if (i % 2) {
      for (long long j = y; j <= m; j++) {
        cout << i << " " << j << " ";
      }
      y = m;
    } else {
      for (long long j = y; j >= 1; j--) {
        cout << i << " " << j << " ";
      }
      y = 1;
    }
  }
}
