#include <bits/stdc++.h>
using namespace std;
map<string, bool> mp;
string ans[105][2];
bool fnd;

void dfs(int i, int n, string u[]) {
    if (fnd) return;
    if (i == n) {
        fnd = true;
        for (int j = 0; j < n; j++) {
            cout << ans[j][0] << " " << ans[j][1] << endl;
        }
        return;
    }
    string s = u[i];
    for (int j = 1; j < 3; j++) {
        string a = s.substr(0, j);
        string b = s.substr(j);
        if (!mp[a] && !mp[b]) {
            mp[a] = mp[b] = true;
            ans[i][0] = a;
            ans[i][1] = b;
            dfs(i + 1, n, u);
            mp[a] = mp[b] = false;
        }
    }
}

int main() {
    int n;
    cin >> n;
    string u[105];
    for (int i = 0; i < n; i++) {
        cin >> u[i];
    }
    fnd = false;
    dfs(0, n, u);
    if (!fnd) {
        cout << "Impossible" << endl;
    }
    return 0;
}