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

const int MAXN = 52;

int N;
string S[ MAXN * 2 ];

vector< int > G[ MAXN * 2 ], rG[ MAXN * 2 ];

void dfs_topo( int u, vector< int > &stk, vector< int > &vis ) {
  for( int v : G[ u ] ) {
    if( vis[ v ] ) continue;
    vis[ v ] = 1;
    dfs_topo( v, stk, vis );
  }
  stk.emplace_back( u );
}

void dfs_ksrj( int u, vector< int > &scc, int scc_id ) {
  for( int v : rG[ u ] ) {
    if( scc[ v ] ) continue;
    scc[ v ] = scc_id;
    dfs_ksrj( v, scc, scc_id );
  }
}

signed main() {
  ios::sync_with_stdio( 0 );
  cin >> N;
  if( N > MAXN ) {
    cout << "Impossible" << endl;
    exit( 0 );
  }
  for( int i = 0; i < N; ++i ) {
    cin >> S[ i ];
  }
  for( int i = 0; i < N; ++i ) {
    for( int j = 0; j < N; ++j ) {
      if( i == j ) continue;
      if( S[ i ][ 0 ] == S[ j ][ 0 ] or S[ i ].substr( 1, 2 ) == S[ j ].substr( 1, 2 ) ) {
        G[ i ].emplace_back( N + j );
        rG[ N + j ].emplace_back( i );
      }
      if( S[ i ][ 0 ] == S[ j ][ 2 ] or S[ i ].substr( 1, 2 ) == S[ j ].substr( 0, 2 ) ) {
        G[ i ].emplace_back( j );
        rG[ j ].emplace_back( i );
      }
      if( S[ i ][ 2 ] == S[ j ][ 0 ] or S[ i ].substr( 0, 2 ) == S[ j ].substr( 1, 2 ) ) {
        G[ N + i ].emplace_back( N + j );
        rG[ N + j ].emplace_back( N + i );
      }
      if( S[ i ][ 2 ] == S[ j ][ 2 ] or S[ i ].substr( 0, 2 ) == S[ j ].substr( 0, 2 ) ) {
        G[ N + i ].emplace_back( j );
        rG[ j ].emplace_back( N + i );
      }
    }
  }
  int scc_cnt = 0;
  vector< int > stk, scc( N * 2 );
  {
    vector< int > vis( N * 2 );
    for( int i = 0; i < N * 2; ++i ) {
      if( vis[ i ] ) continue;
      vis[ i ] = 1;
      dfs_topo( i, stk, vis );
    }
    for( int i = N * 2 - 1; i >= 0; --i ) {
      if( scc[ stk[ i ] ] ) continue;
      scc[ stk[ i ] ] = ++scc_cnt;
      dfs_ksrj( stk[ i ], scc, scc_cnt );
    }
  }
  for( int i = 0; i < N; ++i ) {
    if( scc[ i ] == scc[ N + i ] ) {
      cout << "Impossible" << endl;
      exit( 0 );
    }
  }
  vector< int > sat( scc_cnt + 1 );
  for( int i = N * 2 - 1; i >= 0; --i ) {
    int u = stk[ i ];
    int v = stk[ i ] >= N ? stk[ i ] - N : stk[ i ] + N;
    if( sat[ scc[ u ] ] ) {
      sat[ scc[ v ] ] = 3 - sat[ scc[ u ] ];
    } else if( sat[ scc[ v ] ] ) {
      sat[ scc[ u ] ] = 3 - sat[ scc[ v ] ];
    } else {
      sat[ scc[ u ] ] = 1;
      sat[ scc[ v ] ] = 2;
    }
  }
  for( int i = 0; i < N; ++i ) {
    if( sat[ scc[ i ] ] == 1 ) {
      cout << S[ i ][ 0 ] << " " << S[ i ].substr( 1, 2 ) << "\n";
    } else {
      cout << S[ i ].substr( 0, 2 ) << " " << S[ i ][ 2 ] << "\n";
    }
  }
  return 0;
}