Compilare: user.cpp: In function ‘int64_t sortedDigits(int)’: user.cpp:23:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < digits.size(); ++i) { ~~^~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:32:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pluton.in", "r", stdin); ^ user.cpp:33:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pluton.out", "w", stdout); ^ user.cpp:36:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:41:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^