mere.cpp: In function 'void dfs(int)': mere.cpp:29: warning: comparison between signed and unsigned integer expressions mere.cpp: In function 'int main()': mere.cpp:43: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x mere.cpp:43: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x mere.cpp:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result mere.cpp:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result mere.cpp:39: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result mere.cpp:42: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result