Compilare: user.cpp: In function ‘void read()’: user.cpp:19:19: warning: unused variable ‘z’ [-Wunused-variable] int x, y, z; ^ user.cpp:16:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:20:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^