package invsplust;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;

public class Main {

	public static void main(String[] args) {
		IO io = new IO();
		int n = io.nextInt();
		String[] u = new String[n];
		for(int i=0;i<n;i++) {
			u[i] = io.next();
		}
		solve(n,u,io);
	}
	
	public static void solve(int n, String[] u, PrintWriter io) {
		//nがアルファベットの数より大きいとき不可能
		if (n > 60) {
			io.println("Impossible");
			io.flush();
			return;
		}
		
		//右側で分割するのを真とする
		TwoSAT ts = new TwoSAT(n);
		
		for(int i=0;i<n;i++) {
			String u1 = u[i];
			for(int j=i+1;j<n;j++) {
				String u2 = u[j];
				for(int k=0;k<4;k++) { //2つの文字列の分割の方法2^2=4通り
					int l1 = (k >> 1) & 1;
					int l2 = k & 1;
					String s1 = u1.substring(0, l1 + 1);
					String t1 = u1.substring(l1 + 1, 3);
					String s2 = u2.substring(0, l2 + 1);
					String t2 = u2.substring(l2 + 1, 3);
					//(3文字なのでs1=t1やs2=t2はありえない)
					if (s1.equals(s2) || s1.equals(t2) || t1.equals(s2) || t1.equals(t2)) {
						//ダメなのでこの分割をしたとき0になるような節を追加する
						ts.addClause(l1 == 0, i, l2 == 0, j);
					}
				}
			}
		}
		
		boolean[] right = ts.solve();
		
		if (right == null) {
			io.println("Impossible");
			io.flush();
			return;
		}
		
		for(int i=0;i<n;i++) {
			int len = right[i] ? 2 : 1;
			String s = u[i].substring(0, len);
			String t = u[i].substring(len, 3);
			io.print(s); io.print(' '); io.println(t);
		}
		io.flush();
	}
}
class TwoSAT {
	int n;
	SCC graph;
	public TwoSAT(int n) {
		this.n = n;
		graph = new SCC(n * 2); //¬x0, ..., ¬xn, x0, ..., xn  
	}
	
	//(¬x0 ∨ x1) -> (false, 0, true, 1)
	public void addClause(boolean tf1, int x1, boolean tf2, int x2) {
//		System.out.println((tf1 ? "" : "¬") + x1 + "∨" + (tf1 ? "" : "¬") + x2);
		graph.addEdge(x1 + (tf1 ? 0 : n), x2 + (tf2 ? n : 0)); //¬x1 -> x2
		graph.addEdge(x2 + (tf2 ? 0 : n), x1 + (tf1 ? n : 0)); //¬x2 -> x1
	}
	
	//充足不可能なときnull, そうでなければ真偽の割り当て
	public boolean[] solve() {
		graph.scc();
		int[] order = graph.order;
		boolean[] res = new boolean[n];
		for(int i=0;i<n;i++) {
			if (order[i] == order[i+n]) {
				return null;
			}
			if (order[i+n] > order[i]) {
				res[i] = true;
			}
		}
		return res;
	}
}
class SCC {
	int n;
	ArrayList<Integer>[] graph; //グラフ
	ArrayList<Integer>[] rgraph; //逆辺からなるグラフ
	ArrayList<Integer> vertices; //帰りがけ順に頂点を並べる
	boolean[] used;
	int[] order; //強連結成分のトポロジカル順序
	int sccNum;
	
	@SuppressWarnings("unchecked")
	public SCC(int n) {
		this.n = n;
		graph = new ArrayList[n];
		rgraph = new ArrayList[n];
		for(int i=0;i<n;i++) {
			graph[i] = new ArrayList<>();
			rgraph[i] = new ArrayList<>();
		}
	}
	
	public void addEdge(int from,int to) {
//		System.out.println(from + "->" + to);
		graph[from].add(to);
		rgraph[to].add(from);
	}
	
	private void dfs(int v) {
		used[v] = true;
		for(int u: graph[v]) {
			if (!used[u]) {
				dfs(u);
			}
		}
		vertices.add(v);
	}
	
	private void rdfs(int v, int k) {
		used[v] = true;
		order[v] = k;
		for(int u: rgraph[v]) {
			if (!used[u]) {
				rdfs(u, k);
			}
		}
	}
	
	public void scc() {
		used = new boolean[n];
		order = new int[n];
		vertices = new ArrayList<>();
		sccNum = 0;
		for(int i=0;i<n;i++) {
			if (!used[i]) {
				dfs(i);
			}
		}
		Arrays.fill(used, false);
		for(int i=vertices.size()-1;i>=0;i--) {
			int v = vertices.get(i);
			if (!used[v]) {
				rdfs(v, sccNum++);
			}
		}
	}
	
	//scc()の後に呼び出して強連結成分をトポロジカル順序で返す
	@SuppressWarnings("unchecked")
	public ArrayList<Integer>[] restoreSCCs() {
		ArrayList<Integer>[] res = new ArrayList[sccNum];
		for(int i=0;i<sccNum;i++) {
			res[i] = new ArrayList<>();
		}
		for(int i=0;i<n;i++) {
			res[order[i]].add(i);
		}
		return res;
	}
}
class IO extends PrintWriter {
	private final InputStream in;
	private final byte[] buffer = new byte[1024];
	private int ptr = 0;
	private int buflen = 0;
	
	public IO() { this(System.in);}
	public IO(InputStream source) { super(System.out); this.in = source;}
	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		}else{
			ptr = 0;
			try {
				buflen = in.read(buffer);
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen <= 0) {
				return false;
			}
		}
		return true;
	}
	private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
	private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
	private static boolean isNewLine(int c) { return c == '\n' || c == '\r';}
	public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();}
	public boolean hasNextLine() { while(hasNextByte() && isNewLine(buffer[ptr])) ptr++; return hasNextByte();}
	public String next() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while(isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	public char[] nextCharArray(int len) {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		char[] s = new char[len];
		int i = 0;
		int b = readByte();
		while(isPrintableChar(b)) {
			if (i == len) {
				throw new InputMismatchException();
			}
			s[i++] = (char) b;
			b = readByte();
		}
		return s;
	}
	public String nextLine() {
		if (!hasNextLine()) {
			throw new NoSuchElementException();
		}
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while(!isNewLine(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	public long nextLong() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while(true){
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			}else if(b == -1 || !isPrintableChar(b)){
				return minus ? -n : n;
			}else{
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}
	public int nextInt() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
			throw new NumberFormatException();
		}
		return (int) nl;
	}
	public char nextChar() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		return (char) readByte();
	}
	public double nextDouble() { return Double.parseDouble(next());}
	public int[] nextIntArray(int n) { int[] a = new int[n]; for(int i=0;i<n;i++) a[i] = nextInt(); return a;}
	public long[] nextLongArray(int n) { long[] a = new long[n]; for(int i=0;i<n;i++) a[i] = nextLong(); return a;}
	public double[] nextDoubleArray(int n) { double[] a = new double[n]; for(int i=0;i<n;i++) a[i] = nextDouble(); return a;}
	public void nextIntArrays(int[]... a) { for(int i=0;i<a[0].length;i++) for(int j=0;j<a.length;j++) a[j][i] = nextInt();}
	public int[][] nextIntMatrix(int n,int m) { int[][] a = new int[n][]; for(int i=0;i<n;i++) a[i] = nextIntArray(m); return a;}
	public char[][] nextCharMap(int n,int m) { char[][] a = new char[n][]; for(int i=0;i<n;i++) a[i] = nextCharArray(m); return a;}
	public void close() { super.close(); try {in.close();} catch (IOException e) {}}
}