import java.io.*; import java.util.*; public class Main_yukicoder470_1 { private static Scanner sc; private static Printer pr; private static void solve() { int n = sc.nextInt(); char[][] u = new char[n][]; for (int i = 0; i < n; i++) { u[i] = sc.next().toCharArray(); } if (n > 52) { pr.println("Impossible"); return; } int V = n * 2; SCC scc = new SCC(V); for (int i = 0; i < n; i++) { for (int j = i + 1; j < n; j++) { if (u[i][0] == u[j][0]) { scc.add_edge(i, j + n); scc.add_edge(j, i + n); } if (u[i][1] == u[j][1] && u[i][2] == u[j][2]) { scc.add_edge(i, j + n); scc.add_edge(j, i + n); } if (u[i][2] == u[j][2]) { scc.add_edge(i + n, j); scc.add_edge(j + n, i); } if (u[i][0] == u[j][0] && u[i][1] == u[j][1]) { scc.add_edge(i + n, j); scc.add_edge(j + n, i); } if (u[i][0] == u[j][2]) { scc.add_edge(i, j); scc.add_edge(j + n, i + n); } if (u[i][1] == u[j][0] && u[i][2] == u[j][1]) { scc.add_edge(i, j); scc.add_edge(j + n, i + n); } if (u[i][2] == u[j][0]) { scc.add_edge(i + n, j + n); scc.add_edge(j, i); } if (u[i][0] == u[j][1] && u[i][1] == u[j][2]) { scc.add_edge(i + n, j + n); scc.add_edge(j, i); } } } scc.scc(); for (int i = 0; i < n; i++) { if (scc.cmp[i] == scc.cmp[i + n]) { pr.println("Impossible"); return; } } for (int i = 0; i < n; i++) { if (scc.cmp[i] > scc.cmp[i + n]) { pr.printf("%c %c%c\n", u[i][0], u[i][1], u[i][2]); } else { pr.printf("%c%c %c\n", u[i][0], u[i][1], u[i][2]); } } } // SCC O(V + E) private static class SCC { private int V; private List> edges; private List> redges; // 逆向きの辺 private List vs; // 帰りがけ順の並び private int[] used; // 0:White, 1:Gray, 2:Black private int[] cmp; // 属する強連結成分のトポロジカル順序 private SCC(int V) { this.V = V; edges = new ArrayList<>(V); redges = new ArrayList<>(V); for (int i = 0; i < V; i++) { edges.add(new ArrayList<>()); redges.add(new ArrayList<>()); } vs = new ArrayList<>(V); used = new int[V]; cmp = new int[V]; } private void add_edge(int from, int to) { edges.get(from).add(to); redges.get(to).add(from); } private int scc() { // dfs for (int v = 0; v < V; v++) { if (used[v] != 0) { continue; } Deque st = new ArrayDeque<>(); st.push(v); while (!st.isEmpty()) { int e = st.peek(); if (used[e] == 2) { st.pop(); } else if (used[e] == 1) { // postorder vs.add(e); used[e] = 2; st.pop(); } else { // preorder used[e] = 1; for (int next : edges.get(e)) { if (used[next] == 2) { // 前進辺または横断辺 continue; } else if (used[next] == 1) { // 後退辺 continue; } st.push(next); } } } } Arrays.fill(used, 0); // rdfs int k = 0; for (int i = vs.size() - 1; i >= 0; i--) { int v = vs.get(i); if (used[v] != 0) { continue; } Deque st = new ArrayDeque<>(); st.push(v); while (!st.isEmpty()) { int e = st.peek(); if (used[e] == 2) { st.pop(); } else if (used[e] == 1) { // postorder used[e] = 2; st.pop(); } else { // preorder cmp[e] = k; used[e] = 1; for (int next : redges.get(e)) { if (used[next] == 2) { // 前進辺または横断辺 continue; } else if (used[next] == 1) { // 後退辺 continue; } st.push(next); } } } k++; } return k; } // v が属する強連結成分のトポロジカル順序 private int getCmp(int v) { return cmp[v]; } } // --------------------------------------------------- public static void main(String[] args) { sc = new Scanner(System.in); pr = new Printer(System.out); solve(); pr.close(); sc.close(); } @SuppressWarnings("unused") private static class Scanner { BufferedReader br; Scanner (InputStream in) { br = new BufferedReader(new InputStreamReader(in)); } private boolean isPrintable(int ch) { return ch >= '!' && ch <= '~'; } private boolean isCRLF(int ch) { return ch == '\n' || ch == '\r' || ch == -1; } private int nextPrintable() { try { int ch; while (!isPrintable(ch = br.read())) { if (ch == -1) { throw new NoSuchElementException(); } } return ch; } catch (IOException e) { throw new NoSuchElementException(); } } String next() { try { int ch = nextPrintable(); StringBuilder sb = new StringBuilder(); do { sb.appendCodePoint(ch); } while (isPrintable(ch = br.read())); return sb.toString(); } catch (IOException e) { throw new NoSuchElementException(); } } int nextInt() { try { // parseInt from Integer.parseInt() boolean negative = false; int res = 0; int limit = -Integer.MAX_VALUE; int radix = 10; int fc = nextPrintable(); if (fc < '0') { if (fc == '-') { negative = true; limit = Integer.MIN_VALUE; } else if (fc != '+') { throw new NumberFormatException(); } fc = br.read(); } int multmin = limit / radix; int ch = fc; do { int digit = ch - '0'; if (digit < 0 || digit >= radix) { throw new NumberFormatException(); } if (res < multmin) { throw new NumberFormatException(); } res *= radix; if (res < limit + digit) { throw new NumberFormatException(); } res -= digit; } while (isPrintable(ch = br.read())); return negative ? res : -res; } catch (IOException e) { throw new NoSuchElementException(); } } long nextLong() { try { // parseLong from Long.parseLong() boolean negative = false; long res = 0; long limit = -Long.MAX_VALUE; int radix = 10; int fc = nextPrintable(); if (fc < '0') { if (fc == '-') { negative = true; limit = Long.MIN_VALUE; } else if (fc != '+') { throw new NumberFormatException(); } fc = br.read(); } long multmin = limit / radix; int ch = fc; do { int digit = ch - '0'; if (digit < 0 || digit >= radix) { throw new NumberFormatException(); } if (res < multmin) { throw new NumberFormatException(); } res *= radix; if (res < limit + digit) { throw new NumberFormatException(); } res -= digit; } while (isPrintable(ch = br.read())); return negative ? res : -res; } catch (IOException e) { throw new NoSuchElementException(); } } float nextFloat() { return Float.parseFloat(next()); } double nextDouble() { return Double.parseDouble(next()); } String nextLine() { try { int ch; while (isCRLF(ch = br.read())) { if (ch == -1) { throw new NoSuchElementException(); } } StringBuilder sb = new StringBuilder(); do { sb.appendCodePoint(ch); } while (!isCRLF(ch = br.read())); return sb.toString(); } catch (IOException e) { throw new NoSuchElementException(); } } void close() { try { br.close(); } catch (IOException e) { // throw new NoSuchElementException(); } } } private static class Printer extends PrintWriter { Printer(PrintStream out) { super(out); } } }