charlie.cpp: In function 'int main()': charlie.cpp:5: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result charlie.cpp:6: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result charlie.cpp:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result charlie.cpp:9: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result charlie.cpp:10: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/cc4mEbAz.o: In function `main': charlie.cpp:(.text+0x6f): warning: the `gets' function is dangerous and should not be used.