Compilare: user.cpp: In function ‘std::vector<int> join(std::vector<int>&, std::vector<int>&)’: user.cpp:49:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ((i < left.size()) && (j < right.size())) { ^ user.cpp:49:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ((i < left.size()) && (j < right.size())) { ^ user.cpp:58:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < left.size()) { ^ user.cpp:62:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < right.size()) { ^ user.cpp: In function ‘int main()’: user.cpp:116:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.in", "r", stdin); ^ user.cpp:117:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.out", "w", stdout); ^ user.cpp:119:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:121:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&sorted[i].y); ^ user.cpp:128:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&m); ^ user.cpp:130:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&x1,&x2,&y1,&y2); ^