Compilare: user.cpp: In function ‘std::vector<int> join(std::vector<int>&, std::vector<int>&)’: user.cpp:68:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ((i < left.size()) && (j < right.size())) { ^ user.cpp:68:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ((i < left.size()) && (j < right.size())) { ^ user.cpp:77:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < left.size()) { ^ user.cpp:81:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < right.size()) { ^ user.cpp: In function ‘int main()’: user.cpp:142:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zoo.out", "w", stdout); ^ user.cpp:144:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &N); ^ user.cpp:146:51: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d %d", &sorted[i].x, &sorted[i].y); ^ user.cpp:152:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &M); ^ user.cpp:154:49: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d %d %d %d", &x1, &y1, &x2, &y2); ^