#include <iostream>
#include <string>
#include <unordered_set>
using namespace std;
int main() {
int N, M;
cin >> N >> M; // Taking input for N and M
unordered_set<string> uniqueStrings; // Set to store unique N-length strings
// Taking input for N strings
for (int i = 0; i < N; ++i) {
string input;
cin >> input;
// Iterate over each position (K) in the string
for (int k = 0; k < M; ++k) {
string newString = ""; // New string formed by taking Kth character from each input string
// For each position (K), create a new string
for (int j = 0; j < N; ++j) {
newString += input[j == i ? k : j];
}
uniqueStrings.insert(newString); // Add the newly formed string to the set
}
}
// Output all strings from the set
for (const string& str : uniqueStrings) {
cout << str << endl;
}
return 0;
}
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