A B C D->Z
0 0 0 0 Z=0 
1 0 0 0 Z=1 
1 1 0 0 Z=1 
0 1 0 0 Z=1 
0 1 1 0 Z=1 
1 1 1 0 Z=1 
1 0 1 0 Z=1 
0 0 1 0 Z=1 
0 0 1 1 Z=1 
1 0 1 1 Z=1 
1 1 1 1 Z=1 
0 1 1 1 Z=1 
0 1 0 1 Z=1 
1 1 0 1 Z=1 
1 0 0 1 Z=1 
0 0 0 1 Z=1 
function: Z = !(!A && !B && !C && !D)