spiridusi.cpp: In function 'void df(int)': spiridusi.cpp:63: warning: comparison between signed and unsigned integer expressions spiridusi.cpp: In function 'int main()': spiridusi.cpp:78: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result spiridusi.cpp:79: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result spiridusi.cpp:81: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:83: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:85: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result spiridusi.cpp:91: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result