#include <cstdio>

 #include <cstring>

 #include <cstdlib>

 #include <algorithm>

 #include <vector>

 #include <queue>

 using namespace std;

 const int MAXN = ;

 struct LLL

 {

     int lf;

     LLL( int nn =  ): lf(nn) { }

     bool operator<( const LLL& rhs ) const

     {

         return lf > rhs.lf;

     }

 };

 int vis[MAXN];

 vector<int> Tr[MAXN];

 int num[MAXN];

 priority_queue<LLL> leaf;

 int main()

 {

     int cnt = ;

     int N = ;

     while ( scanf( "%d", &num[cnt] ) != EOF )

     {

         N = max( N, num[cnt] );

         ++cnt;

     }

     memset( vis, , sizeof(vis) );

     for ( int i = ; i < cnt; ++i )

         ++vis[ num[i] ];

     for ( int i = ; i <= N; ++i )

         if ( vis[i] ==  ) leaf.push( LLL(i) );

     for ( int i = ; i <= cnt; ++i ) Tr[i].clear();

     int i, j;

     for ( i = ; i < cnt; ++i )

     {

         LLL tmp = leaf.top();

         leaf.pop();

         Tr[ num[i] ].push_back( tmp.lf );

         Tr[ tmp.lf ].push_back( num[i] );

         --vis[ num[i] ];

         if ( vis[ num[i] ] ==  )

             leaf.push( LLL( num[i] ) );

     }

     for ( i = ; i <= N; ++i )

     {

         printf( "%d:", i );

         sort( Tr[i].begin(), Tr[i].end() );

         int sz = Tr[i].size();

         for ( j = ; j < sz; ++j )

             printf(" %d", Tr[i][j] );

         puts("");

     }

     return ;

 }