20
\\/\/\/\/\/\/\/\/\/\
/\\/\/\/\/\/\/\/\/\/
\/................/\
/\................\/
\/................/\
/\................\/
\/................/\
/\................\/
\/................/\
/\................\/
\/................/\
/\................\/
\/................/\
/\................\/
\/................/\
/\................\/
\/................/\
/\................\/
\/\/\/\/\/\/\/\/\//\
/\/\/\/\/\/\/\/\/\//