sub.cpp: In function 'int main()': sub.cpp:59: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sub.cpp:60: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sub.cpp:63: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sub.cpp:67: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result sub.cpp:76: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sub.cpp:78: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/cc0scdWy.o: In function `main': sub.cpp:(.text+0xc0): warning: the `gets' function is dangerous and should not be used.