#include <algorithm>
#include <iostream>
#include <vector>
#include <set>
using namespace std;

struct StronglyConnectedComponents {
    int id = 0;
    vector<vector<int>> gg, rg;
    vector<int> comp, order, seen, depth;
    StronglyConnectedComponents(int v) : \
    gg(v), rg(v), comp(v, -1), seen(v, 0), depth(v, 1) { }
    void add_edge(int x, int y) {
        gg[x].emplace_back(y);
        rg[y].emplace_back(x);
    }
    void dfs(int u) {           // order, seen
        seen[u] = true;
        for (int v: gg[u]) if (!seen[v]) dfs(v);
        order.emplace_back(u);
    }
    void rdfs(int u, int id) {  // comp, depth
        comp[u] = id;
        for (int v: rg[u]) {
            if (comp[v] == -1) rdfs(v, id);
            depth[u] = max(depth[u], depth[v] + 1);
        }
    }
    int build() {
        for (int u = 0; u < gg.size(); ++u) if (!seen[u]) dfs(u);
        reverse(begin(order), end(order));
        for (int u: order) if (comp[u] == -1) rdfs(u, id++);
        return id;
    }
    vector<vector<int>> make_graph() {
        vector<vector<int>> g_comp(id);
        set<pair<int, int>> connect;
        for (int u = 0; u < gg.size(); ++u) for (int v: gg[u]) {
            int x = comp[u], y = comp[v];
            if (x == y) continue;
            if (connect.count({x, y})) continue;
            g_comp[x].emplace_back(y);
            connect.emplace(x, y);
        }
        return g_comp;
    }
    int operator[](int k) { return comp[k]; }
};

struct TwoSatisfiability : StronglyConnectedComponents {
    int sz;
    TwoSatisfiability(int v) : StronglyConnectedComponents(v + v), sz(v) {}
    void add_if(int u, int v) {                         // u -> v <=> ¬v -> ¬u
        add_edge(u, v); add_edge(neg(v), neg(u));
    }
    void add_or(int u, int v) { add_if(neg(u), v); }    //  u or v  <=> ¬u -> v
    void add_nand(int u, int v) { add_if(u, neg(v)); }  // ¬(u ∧ v) <=> u -> ¬v
    void set_true(int v) { add_edge(neg(v), v); }       //  v <=> ¬v -> v
    void set_false(int v) { add_edge(v, neg(v)); }      // ¬v <=>  v -> ¬v
    int neg(int x) { return (x + sz) % (sz * 2); }
    bool solve() {
        build();
        for (int i = 0; i < sz; i++) {
            if ((*this)[i] == (*this)[neg(i)]) return false;
        }
        return true;
    }
    bool operator()(int v) { return (*this)[v] > (*this)[neg(v)]; }
};

int main() {
    int n; cin >> n;
    vector<string> u(n);
    for (string& ui: u) cin >> ui;
    if (n > 26 * 2) return !(cout << "Impossible" << endl);
    TwoSatisfiability ts(n);
    #define NOT(i) ts.neg(i)
    for (int i = 0; i < n; i++) for (int j = 0; j < i; j++) {
        auto &sa = u[i], &sb = u[j];
        if (sa.substr(0, 2) == sb.substr(0, 2) || sa[2] == sb[2])
            ts.add_nand(i, j);
        if (sa.substr(0, 2) == sb.substr(1, 2) || sa[2] == sb[0])
            ts.add_nand(i, NOT(j));
        if (sa.substr(1, 2) == sb.substr(0, 2) || sa[0] == sb[2])
            ts.add_nand(NOT(i), j);
        if (sa.substr(1, 2) == sb.substr(1, 2) || sa[0] == sb[0])
            ts.add_nand(NOT(i), NOT(j));
    }
    if (!ts.solve()) return !(cout << "Impossible" << endl);;
    for (int i = 0; i < n; i++) {
        if (ts(i)) cout << u[i].substr(0, 2) << " " << u[i].substr(2, 1) << endl;
        else cout << u[i].substr(0, 1) << " " << u[i].substr(1, 2) << endl;
    }
    return 0;
}