#include <iostream>
#include <map>
#include <string>
#include <vector>
using namespace std;

int n, m, k;
map<string, int> mp;
vector<string> a;

int main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    cin >> n >> m >> k, a.resize(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) mp[a[i].substr(j * k, k)]++;
    }

    string pattern;
    for (auto &[s, c] : mp) {
        if (c == 1) {
            pattern = s;
            break;
        }
    }

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (a[i].substr(j * k, k) == pattern) {
                cout << i + 1 << " " << j + 1 << '\n';
                return 0;
            }
        }
    }
}