Initial state the pressure and volume are
P = 1 bar
V = 1 litre
Now the process equation is given as
PV = constant
So now the pressure is increased to
P = 4 bar
so volume must decrease by 4 times
so final volume is
V = 0.25 litre
Now the pressure is constant and volume again increased to V = 1 litre
Now in final step the volume will become constant and again pressure will become P = 1 bar
so this is a cyclic process and figure is attached at following