Compilare: user.cpp: In function ‘void add(int, int)’: user.cpp:14:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < h[r].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:46:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < h[i].size(); ++j) ^ user.cpp:28:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pariuri.in","r",stdin); ^ user.cpp:29:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pariuri.out","w",stdout); ^ user.cpp:33:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^ user.cpp:36:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&M); ^ user.cpp:39:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^