foo.cc: In function 'void print_by_2(int)':
foo.cc:12:2: error: 'itoa' was not declared in this scope
  itoa(val,buf,2);
  ^~~~
foo.cc:12:2: note: suggested alternative: 'atol'
  itoa(val,buf,2);
  ^~~~
  atol
foo.cc: In function 'void bfs()':
foo.cc:43:1: error: a function-definition is not allowed here before '{' token
 {
 ^
foo.cc:68:1: error: expected '}' at end of input
 }
 ^

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