Compilare: user.cpp: In function ‘void add(int, int, int)’: user.cpp:34: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void query(int, int)’: user.cpp:53: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void prefix(int, int)’: user.cpp:63: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:70: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:71: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result /tmp/cc3LX7l5.o: In function `main': user.cpp:(.text+0x420): warning: the `gets' function is dangerous and should not be used.