Compilare: user.cpp: In function ‘int main()’: user.cpp:159:9: warning: unused variable ‘prv’ [-Wunused-variable] int prv = 1; ^ user.cpp:137:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:140:73: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &v[i].a.x, &v[i].a.y, &v[i].b.x, &v[i].b.y); ^