dp.cpp: In function 'int main()': dp.cpp:27: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result dp.cpp:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result dp.cpp:30: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/cc9Fv4jZ.o: In function `main': dp.cpp:(.text+0xe6): warning: the `gets' function is dangerous and should not be used.