blis.cpp: In function 'int main()': blis.cpp:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result blis.cpp:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result blis.cpp:41: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result blis.cpp:42: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/ccHhgC3K.o: In function `main': blis.cpp:(.text+0xbf): warning: the `gets' function is dangerous and should not be used.