#include <bits/stdc++.h>
#ifdef LOCAL
#include <debug.hpp>
#else
#define debug(...) void(0)
#endif

template <class T> std::istream& operator>>(std::istream& is, std::vector<T>& v) {
    for (auto& e : v) {
        is >> e;
    }
    return is;
}

template <class T> std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) {
    for (std::string_view sep = ""; const auto& e : v) {
        os << std::exchange(sep, " ") << e;
    }
    return os;
}

template <class T, class U = T> bool chmin(T& x, U&& y) {
    return y < x and (x = std::forward<U>(y), true);
}

template <class T, class U = T> bool chmax(T& x, U&& y) {
    return x < y and (x = std::forward<U>(y), true);
}

template <class T> void mkuni(std::vector<T>& v) {
    std::ranges::sort(v);
    auto result = std::ranges::unique(v);
    v.erase(result.begin(), result.end());
}

template <class T> int lwb(const std::vector<T>& v, const T& x) {
    return std::distance(v.begin(), std::ranges::lower_bound(v, x));
}

using namespace std;

using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);

    int n, m, k;
    cin >> n >> m >> k;
    vector<string> S(n);
    cin >> S;

    map<string, vector<pair<int, int>>> mp;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            string s = S[i].substr(j * k, k);
            mp[s].emplace_back(i, j);
        }
    }
    for (auto [key, val] : mp) {
        if (val.size() == 1) {
            auto [x, y] = val[0];
            cout << x + 1 << " " << y + 1 << "\n";
            return 0;
        }
    }
    return 0;
}