Sideways Sorting Solution:

#include <bits/stdc++.h>
using namespace std;

int main(){
    // #ifndef TESTING
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
    // #endif

    int nWords, chars;
    cin >> nWords >> chars;
    while(nWords > 0){
        string words[chars];
        for(int i = 0; i < nWords; i++){
            for(int j = 0; j < chars; j++){
                char c;
                cin >> c;
                words[j].push_back(c);
            }
        }
        sort(words, words + chars, [](string a, string b){
            transform(a.begin(), a.end(), a.begin(), [](unsigned char c){
                return tolower(c);
            });
            transform(b.begin(), b.end(), b.begin(), [](unsigned char c){
                return tolower(c);
            });
            return a < b;
        });
        for(int i = 0; i < nWords; i++){
            for(int j = 0; j < chars; j++){
                cout << words[j][i];
            }
            cout << endl;
        }
        cout << endl;
        cin >> nWords >> chars;
    }
    
    return 0;   
}