spiridusi.cpp: In function 'void df(int)': spiridusi.cpp:36: warning: comparison between signed and unsigned integer expressions spiridusi.cpp: In function 'int main()': spiridusi.cpp:44: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result spiridusi.cpp:45: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result spiridusi.cpp:46: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:47: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:48: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:51: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result