Q2 [5] Moving average Suppose a:NR is an infinite sequence. Define f:Z+R by f(i)=(a(i1)+a(i)+a(i+1))/3,foralliZ+ where Z+={iZi>0}. Consider this algorithm in which x,y, and z are real, p and N are integer, b is real sequence of at least N items. {N>0}x,y:=a(0),a(1)p:=1{I}whilep=Ndoz:=a(p+1)b(p):=(x+y+z)/3x,y:=y,zp:=p+1endwhile{i{1,..N}b(i)=f(i)} State a loop invariant I that could be used to verify this algorithm