foo.cc: In function 'void dfs(int, int)':
foo.cc:49:12: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   49 |         if (p != i)
      |            ^
foo.cc:56:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   56 |     if (tmp + 1 >> 1) {
      |         ~~~~^~~

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