Compilare: user.cpp: In function ‘int main()’: user.cpp:29:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < a[j].size(); ++ k) ^ user.cpp:34:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a[0].size(); ++ i) ^ user.cpp:13:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(F, "%d %d", &n, &m); ^ user.cpp:16:43: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(F, "%d %d %d ", &x, &y, &z); ^