Compilare: user.cpp: In function ‘int main()’: user.cpp:44:119: warning: operation on ‘a[(xv + -1)][(yv + -1)]’ may be undefined [-Wsequence-point] a[xv-2][yv]=a[xv+2][yv]=a[xv][yv-2]=a[xv][yv+2]=a[xv+1][yv+1]=a[xv-1][yv-1]=a[xv+1][yv+1]=a[xv-1][yv-1]=-1; ^ user.cpp:44:119: warning: operation on ‘a[(xv + 1)][(yv + 1)]’ may be undefined [-Wsequence-point]