\[\boxed{\mathbf{1}\mathbf{.207}}\]
| \[\mathbf{1\ рейс}\] | \[\mathbf{А,\ Н,\ Я}\] | \[\mathbf{А,\ Н}\] | \[\mathbf{А,\ Н}\] | \[\mathbf{Н,\ Я}\] | \[\mathbf{Н,\ Я}\] | \[\mathbf{А,\ Я}\] | \[\mathbf{А,\ Я}\] | \[\mathbf{А}\] | \[\mathbf{Я}\] |
|---|---|---|---|---|---|---|---|---|---|
| \[\mathbf{2\ рейс}\] | \[\mathbf{-}\] | \[\mathbf{Я}\] | \[\mathbf{-}\] | \[\mathbf{А}\] | \[\mathbf{-}\] | \[\mathbf{Н}\] | \[\mathbf{-}\] | \[\mathbf{Н,\ Я}\] | \[\mathbf{Н}\] |
| \[\mathbf{3\ рейс}\] | \[\mathbf{-}\] | \[\mathbf{-}\] | \[\mathbf{Я}\] | \[\mathbf{-}\] | \[\mathbf{А}\] | \[\mathbf{-}\] | \[\mathbf{Н}\] | \[\mathbf{-}\] | \[\mathbf{А}\] |
| \[\mathbf{А}\] | \[\mathbf{Н}\] | \[\mathbf{Н}\] | \[\mathbf{Я}\] | \[\mathbf{Я}\] | \[\mathbf{-}\] | \[\mathbf{-}\] | \[\mathbf{А}\] | \[\mathbf{Н}\] | \[\mathbf{Я}\] | \[\mathbf{А}\] | \[\mathbf{Н}\] |
|---|---|---|---|---|---|---|---|---|---|---|---|
| \[\mathbf{-}\] | \[\mathbf{А,\ Я}\] | \[\mathbf{-}\] | \[\mathbf{А,\ Н}\] | \[\mathbf{-}\] | \[\mathbf{А,\ Н,\ Я}\] | \[\mathbf{-}\] | \[\mathbf{Н}\] | \[\mathbf{Я}\] | \[\mathbf{А}\] | \[\mathbf{Я}\] | \[\mathbf{А}\] |
| \[\mathbf{Н,\ Я}\] | \[\mathbf{-}\] | \[\mathbf{А,\ Я}\] | \[\mathbf{-}\] | \[\mathbf{А,\ Н}\] | \[\mathbf{-}\] | \[\mathbf{А,\ Н,\ Я}\] | \[\mathbf{Я}\] | \[\mathbf{А}\] | \[\mathbf{Н}\] | \[\mathbf{Н}\] | \[\mathbf{Я}\] |
\[Если\ три\ рейса,\ \]
\[то\ есть\ 21\ вариант,\ как\ доехать\ \]
\[до\ реки.\]