Compilare: user.cpp: In function ‘int afisare()’: user.cpp:16:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int backt(int)’: user.cpp:31:11: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(valid(k)) ^ user.cpp:40:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^