Compilare: user.cpp: In function ‘void v2()’: user.cpp:34:25: warning: operation on ‘n’ may be undefined [-Wsequence-point] a[++n]=a[n-1]+a[n-2]; ^ user.cpp:34:25: warning: operation on ‘n’ may be undefined [-Wsequence-point] user.cpp:29:16: warning: unused variable ‘y’ [-Wunused-variable] {long long i,x,y,z; ^ user.cpp:29:18: warning: unused variable ‘z’ [-Wunused-variable] {long long i,x,y,z; ^