Compilare: user.cpp: In function ‘int main()’: user.cpp:40:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(st.empty() || ((st.top() & GP) << 2) != x) { ^ user.cpp:17:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j; ^ user.cpp:18:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("paranteze.in", "r", stdin); ^ user.cpp:19:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("paranteze.out", "w", stdout); ^ user.cpp:20:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &N); ^ user.cpp:21:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccgoPYQr.o: In function `main': user.cpp:(.text.startup+0x6a): warning: the `gets' function is dangerous and should not be used.