Compilare: user.cpp: In function ‘int main()’: user.cpp:131:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(ii = 0; ii < sol.size(); ii++) ^ user.cpp:132:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] printf("%d%c", sol[ii], ((ii == sol.size() - 1)?'}':',')); ^ user.cpp:50:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expr.in", "r", stdin); ^ user.cpp:51:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expr.out", "w", stdout); ^ user.cpp:53:28: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(expr, MAXLEN, stdin); ^