// Program 6 - Assemble triads into dimers
molecule    gettriad( string mname )
{
    molecule    m;
    point       p1, p2, p3, pc;
    matrix      mat;
//triad
    if( mname == "a" ){
        m = getpdb( "ata_min.pdb" );
        setpoint( m, "A:DA:C1'", p1 );
        setpoint( m, "B:DT:C1'", p2 );
        setpoint( m, "C:DA:C1'", p3 );
    }else if( mname == "c" ){
        m = getpdb( "cgc.triad.min.pdb" );
        setpoint( m, "A:DC:C1'", p1 );
        setpoint( m, "B:DG:C1'", p2 );
        setpoint( m, "C:DC:C1'", p3 );
    }else if( mname == "g" ){
        m = getpdb( "gcg_min.pdb" );
        setpoint( m, "A:DG:C1'", p1 );
        setpoint( m, "B:DC:C1'", p2 );
        setpoint( m, "C:DG:C1'", p3 );
    }else if( mname == "t" ){
        m = getpdb( "tat.triad.min.pdb" );
        setpoint( m, "A:DT:C1'", p1 );
        setpoint( m, "B:DA:C1'", p2 );
        setpoint( m, "C:DT:C1'", p3 );
    }else if( mname == "p" ){      //p stands for the protonated cytosine
        m = getpdb( "cgc+.pdb" );
        setpoint( m, "A:DC:C1'", p1 );
        setpoint( m, "B:DG:C1'", p2 );
        setpoint( m, "C:DP:C1'", p3 );
    }
    circle( p1, p2, p3, pc );
    mat = newtransform( -pc.x, -pc.y, -pc.z, 0.0, 0.0, 0.0 );
    transformmol( mat, m, NULL );
    setreskind( m, NULL, "DNA" );
    return( m );

};

int mk_dimer( string t )
{
    molecule    mi, mj, mk, mn;
    matrix      mat;
    float       ri, tw;
    string      ifname, sfname, mfname, namei, name3, name5, ti, tj, tk, tn;
    int         n, i;

    ri = 3.2; //rise
    tw = 25;  //twist

    n = length( t ); //n is the strand length
    ti = substr( t, 1, 1);
    mi = gettriad( ti );
    
    mat = newtransform( 0.0, 0.0, ri, 0.0, 0.0, -tw );
           transformmol( mat, mi, NULL );

   for( i = 1; i <= n-1; i = i + 1 ){ 
    tj = substr( t, i+1, 1);
    mj = gettriad( tj );

           mat = newtransform( 0.0, 0.0, ri+3*i, 0.0, 0.0, -(tw+tw*i) );
           transformmol( mat, mj, NULL );

            mergestr( mi, "A", "last", mj, "A", "first" );
            mergestr( mi, "B", "first", mj, "B", "last" );
            mergestr( mi, "C", "last", mj, "C", "first" );
            connectres( mi, "A", 1, "O3'", 2, "P" );
            connectres( mi, "B", 1, "O3'", 2, "P" );
            connectres( mi, "C", 1, "O3'", 2, "P" );           
 }
           sfname = sprintf( "david_%s.pdb", t );
            putpdb( sfname, mi );   // starting coords  
 
};

string t;
scanf( "%s", t );
mk_dimer( t );