Compilare: user.cpp: In function ‘void merge(int, int, int, int)’: user.cpp:40:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < tmp.size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:59:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("inv.in", "r", stdin); ^ user.cpp:60:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("inv.out", "w", stdout); ^ user.cpp:62:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:65:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^