foo.cpp: In function 'int cao(int)':
foo.cpp:9:27: error: 'memset' was not declared in this scope
foo.cpp: In function 'int bfs(int)':
foo.cpp:50:5: warning: no return statement in function returning non-void [-Wreturn-type]
foo.cpp: In function 'int work(int)':
foo.cpp:58:5: warning: no return statement in function returning non-void [-Wreturn-type]