/in/foo.cc: In function 'int dfs(int)':
/in/foo.cc:50:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int read()':
/in/foo.cc:55:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   if(ch=='-') v=-1;ch=getchar();
   ^~
/in/foo.cc:55:20: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
   if(ch=='-') v=-1;ch=getchar();
                    ^~