at(x, a) xa on(x) x = 1x = 0 have(x) x = 1x = 0 get(x) x = 1,x=0MBA at(M,a)at(B,b)have(c)on(0)get(0)at(M,c)at(B,c)on(1)get(1)1goto(a,b)ab at(M, a) on(0) at(M, b) on(0) !at(M, a)2 pushbox(a,b)ab at(M, a) at(B, a) on(0) at(M, b) at(B, b) on(0) !at(M, a) !at(B, a)3climbupbox() at(M, a) at(B, a) on(0) at(M, a) at(B, a) on(1) !on(0)4climbdownbox(a)at(M, a) at(B, a) on(1) at(M, a) at(B, a) on(0) !on(1)5grasp(c) at(M,c) at(B,c) have(c) on(1) get(0) at(M,c) at(B,c) have(c) on(1) get(1) !get(0)