Compilare: user.cpp: In function ‘int main()’: user.cpp:36:43: warning: operation on ‘n’ may be undefined [-Wsequence-point] a[ ++n ] = a[n - 1] + a[n - 2]; ^ user.cpp:36:43: warning: operation on ‘n’ may be undefined [-Wsequence-point] user.cpp:34:32: warning: unused variable ‘y’ [-Wunused-variable] long long i, x , y , z; ^ user.cpp:34:36: warning: unused variable ‘z’ [-Wunused-variable] long long i, x , y , z; ^