G3.1 The figure below is a route map for a postman: starting from the post office, reaching twelve locations to deliver mail, and finally returning to the post office. If the postman takes ten minutes to walk from one location to another and $K$ is the number of hours required for the postman to complete the entire route, find the smallest possible value of $K$.
The figure below represents routes of a postman. Starting at the post office, the postman walks through all the 12 points and finally returns to the post office. If he takes 10 minutes from a point to another adjacent point by walk and $K$ is the number of hours required for the postman to finish the routes, find the smallest possible value of $K$.
$$
\begin{array}{l}
\text { Post Office } \rightarrow \mathrm{A} \rightarrow \mathrm{C} \rightarrow \mathrm{G} \rightarrow \mathrm{C} \rightarrow \mathrm{H} \rightarrow \mathrm{C} \rightarrow \mathrm{A} \rightarrow \mathrm{D} \rightarrow \mathrm{I} \rightarrow \mathrm{D} \rightarrow \mathrm{J} \rightarrow \mathrm{D} \rightarrow \mathrm{A} \rightarrow \text { Post Office } \\
\rightarrow \mathrm{B} \rightarrow \mathrm{E} \rightarrow \mathrm{K} \rightarrow \mathrm{E} \rightarrow \mathrm{L} \rightarrow \mathrm{E} \rightarrow \mathrm{B} \rightarrow \mathrm{F} \rightarrow \mathrm{B} \rightarrow \text { Post Office } \\
\text { Total time }=240 \text { minutes }=4 \text { hours } \\
K=4
\end{array}
$$

Remark The least possible value should be changed to the minimum possible value.