spiridusi.cpp: In function 'int main()': spiridusi.cpp:70: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result spiridusi.cpp:71: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result spiridusi.cpp:73: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:76: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:79: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:84: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp: In function 'void dfs(int)': spiridusi.cpp:44: warning: 'ras' may be used uninitialized in this function