Compilare: user.cpp: In function ‘int main()’: user.cpp:54:63: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = (int) stk2.size(); k < stk1.size(); ++k) ^ user.cpp:27:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("slide.in" , "r", stdin ); ^ user.cpp:28:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("slide.out", "w", stdout); ^ user.cpp:30:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", str + 1); ^