foo.cc: In function ‘int main()’:
foo.cc:24:40: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
   24 |                     if(chan==0||chan==1&&ch[j]==ch[j+1])//chan==1最多变两个相邻的
      |                                 ~~~~~~~^~~~~~~~~~~~~~~~
foo.cc:23:19: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wdangling-else]
   23 |                 if(ch[j])
      |                   ^