\vspace{2mm}\par
\rnode{A}{\opcopy{14}{a}\opprint{a}}\kern1.5cm\rnode{B}{\opadd*{a}{10}{a}\opprint{a}}\kern1.5cm\rnode{C}{\opadd*{a}{10}{a}\opprint{a}}\kern1.5cm\rnode{D}{\phantom{14}}\kern1.5cm\rnode{E}{\phantom{14}}\kern1.5cm\rnode{F}{\phantom{14}.}
\ncline[nodesep=1mm]{->}{A}{B}\ncline[nodesep=1mm]{->}{B}{C}\ncline[nodesep=1mm]{->}{C}{D}\ncline[nodesep=1mm]{->}{D}{E}\ncline[nodesep=1mm]{->}{E}{F}
\par\vspace{2mm}\par\hfill
\rnode{A}{\opcopy{23}{a}\opprint{a}}\kern1.5cm\rnode{B}{\opadd*{a}{9}{a}\opprint{a}}\kern1.5cm\rnode{C}{\opadd*{a}{9}{a}\opprint{a}}\kern1.5cm\rnode{D}{\phantom{14}}\kern1.5cm\rnode{E}{\phantom{14}}\kern1.5cm\rnode{F}{\phantom{14}.}
\ncline[nodesep=1mm]{->}{A}{B}\ncline[nodesep=1mm]{->}{B}{C}\ncline[nodesep=1mm]{->}{C}{D}\ncline[nodesep=1mm]{->}{D}{E}\ncline[nodesep=1mm]{->}{E}{F}
\par\vspace{2mm}\par
\rnode{A}{\opcopy{16}{a}\opprint{a}}\kern1.5cm\rnode{B}{\opadd*{a}{11}{a}\opprint{a}}\kern1.5cm\rnode{C}{\opadd*{a}{11}{a}\opprint{a}}\kern1.5cm\rnode{D}{\phantom{14}}\kern1.5cm\rnode{E}{\phantom{14}}\kern1.5cm\rnode{F}{\phantom{14}.}
\ncline[nodesep=1mm]{->}{A}{B}\ncline[nodesep=1mm]{->}{B}{C}\ncline[nodesep=1mm]{->}{C}{D}\ncline[nodesep=1mm]{->}{D}{E}\ncline[nodesep=1mm]{->}{E}{F}
\par\vspace{2mm}\par\hfill
\rnode{A}{\opcopy{7}{a}\opprint{a}}\kern1.5cm\rnode{B}{\opadd*{a}{20}{a}\opprint{a}}\kern1.5cm\rnode{C}{\opadd*{a}{20}{a}\opprint{a}}\kern1.5cm\rnode{D}{\phantom{14}}\kern1.5cm\rnode{E}{\phantom{14}}\kern1.5cm\rnode{F}{\phantom{14}.}
\ncline[nodesep=1mm]{->}{A}{B}\ncline[nodesep=1mm]{->}{B}{C}\ncline[nodesep=1mm]{->}{C}{D}\ncline[nodesep=1mm]{->}{D}{E}\ncline[nodesep=1mm]{->}{E}{F}
\par\vspace{2mm}\par
\rnode{A}{\opcopy{14}{a}\opprint{a}}\kern1.5cm\rnode{B}{\opadd*{a}{19}{a}\opprint{a}}\kern1.5cm\rnode{C}{\opadd*{a}{19}{a}\opprint{a}}\kern1.5cm\rnode{D}{\phantom{14}}\kern1.5cm\rnode{E}{\phantom{14}}\kern1.5cm\rnode{F}{\phantom{14}.}
\ncline[nodesep=1mm]{->}{A}{B}\ncline[nodesep=1mm]{->}{B}{C}\ncline[nodesep=1mm]{->}{C}{D}\ncline[nodesep=1mm]{->}{D}{E}\ncline[nodesep=1mm]{->}{E}{F}
\par\vspace{2mm}\par\hfill
\rnode{A}{\opcopy{15}{a}\opprint{a}}\kern1.5cm\rnode{B}{\opadd*{a}{12}{a}\opprint{a}}\kern1.5cm\rnode{C}{\opadd*{a}{12}{a}\opprint{a}}\kern1.5cm\rnode{D}{\phantom{15}}\kern1.5cm\rnode{E}{\phantom{15}}\kern1.5cm\rnode{F}{\phantom{15}.}
\ncline[nodesep=1mm]{->}{A}{B}\ncline[nodesep=1mm]{->}{B}{C}\ncline[nodesep=1mm]{->}{C}{D}\ncline[nodesep=1mm]{->}{D}{E}\ncline[nodesep=1mm]{->}{E}{F}