Compilare: user.cpp: In function ‘int main()’: user.cpp:31:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<=s.size()+1; i++) ~^~~~~~~~~~~~ user.cpp:32:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<=s.size()+1; j++) ~^~~~~~~~~~~~ user.cpp:18:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("brackets2.in","r",stdin); ^ user.cpp:19:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("brackets2.out","w",stdout); ^ user.cpp:26:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &t); ^ user.cpp:29:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", c); ^