/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:13:18: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   13 | #define R(i,a,b) for(int i=(a),I=(b);i<I;i++)
      |                  ^~~
/in/foo.cc:43:9: note: in expansion of macro 'R'
   43 |         R(i,0,n)
      |         ^
/in/foo.cc:44:31: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   44 |                 vis[i]=false; match(s)?dfs(J,s+1):void();
      |                               ^~~~~