Compilare: user.cpp: In function ‘int main()’: user.cpp:81:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("x.in", "r", stdin); ^ user.cpp:82:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("x.out", "w", stdout); ^ user.cpp:84:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d\n", &n, &m, &q); ^ user.cpp:85:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a + 1); ^ user.cpp:86:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(b + 1); ^ user.cpp: In member function ‘char Reader::gChar()’: user.cpp:27:42: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff, buffer, 1, stdin); ^ /tmp/cczho3BJ.o: In function `main': user.cpp:(.text.startup+0x7a): warning: the `gets' function is dangerous and should not be used.