#if __INCLUDE_LEVEL__ == 0

#include __BASE_FILE__

void Solve() {
  int n, m, k;
  IN(n, m, k);
  vector<string> s(n);
  IN(s);
  map<string, int> mp;
  for (int i : Rep(0, n)) {
    for (int j : Rep(0, m)) {
      ++mp[s[i].substr(j * k, k)];
    }
  }
  for (int i : Rep(0, n)) {
    for (int j : Rep(0, m)) {
      if (mp[s[i].substr(j * k, k)] == 1) {
        OUT(i + 1, j + 1);
        return;
      }
    }
  }
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  Solve();
}

#elif __INCLUDE_LEVEL__ == 1

#include <bits/stdc++.h>

template <class T> concept Range = std::ranges::range<T> && !std::convertible_to<T, std::string_view>;
template <class T> concept Tuple = std::__is_tuple_like<T>::value && !Range<T>;

namespace std {

istream& operator>>(istream& is, Range auto&& r) {
  for (auto&& e : r) is >> e;
  return is;
}
istream& operator>>(istream& is, Tuple auto&& t) {
  apply([&](auto&... xs) { (is >> ... >> xs); }, t);
  return is;
}

ostream& operator<<(ostream& os, Range auto&& r) {
  auto sep = "";
  for (auto&& e : r) os << exchange(sep, " ") << e;
  return os;
}
ostream& operator<<(ostream& os, Tuple auto&& t) {
  auto sep = "";
  apply([&](auto&... xs) { ((os << exchange(sep, " ") << xs), ...); }, t);
  return os;
}

}  // namespace std

using namespace std;

#define Rep(...) [](int l, int r) { return views::iota(min(l, r), r); }(__VA_ARGS__)
#define IN(...) (cin >> forward_as_tuple(__VA_ARGS__))
#define OUT(...) (cout << forward_as_tuple(__VA_ARGS__) << '\n')

#endif  // __INCLUDE_LEVEL__ == 1