select.cpp: In function 'int main()': select.cpp:74: warning: comparison between signed and unsigned integer expressions select.cpp:85: warning: comparison between signed and unsigned integer expressions select.cpp:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result select.cpp:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result select.cpp:44: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result