sort2dist.cpp: In function 'int main()': sort2dist.cpp:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sort2dist.cpp:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sort2dist.cpp:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sort2dist.cpp:17: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/cc3WtymE.o: In function `main': sort2dist.cpp:(.text+0xd8): warning: the `gets' function is dangerous and should not be used.