blis.cpp: In function 'int main()': blis.cpp:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result blis.cpp:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result blis.cpp:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result blis.cpp:15: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/cctFUdYN.o: In function `main': blis.cpp:(.text+0xff): warning: the `gets' function is dangerous and should not be used.