Compilare: user.cpp:47:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main(){ ^ user.cpp: In function ‘void read()’: user.cpp:40:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&mod); ^ user.cpp:42:39: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d",&L1,&C1,&L2,&C2); ^