On the fourth stage, the player have to deal with bigger room and walls.
Step by step solution
From the initial position, go RIGHT, DOWN, push RIGHT, go DOWN, push RIGHT, go DOWN, RIGHT, DOWN, push RIGHT, go DOWN, push RIGHT, RIGHT, go UP and RIGHT.
Now go RIGHT, push RIGHT, go DOWN, push LEFT, go UP, LEFT, push LEFT, go RIGHT, RIGHT, DOWN, push LEFT, go UP, LEFT, push LEFT, go RIGHT.
Go RIGHT, DOWN, RIGHT, push RIGHT, RIGHT, go UP, RIGHT, UP, UP, push LEFT, LEFT, go RIGHT, RIGHT, DOWN and DOWN.
Go LEFT, DOWN, LEFT, push LEFT, LEFT, go UP, LEFT, LEFT, push LEFT, go DOWN, push RIGHT, RIGHT, go UP, push RIGHT and RIGHT.
Go LEFT, LEFT, DOWN, push LEFT, LEFT, go UP, push LEFT, go UP, push RIGHT, go UP, push RIGHT, RIGHT, RIGHT, go UP, RIGHT and UP.
Go RIGHT, RIGHT, RIGHT and RIGHT.
Congratulations. You have completed the fourth level. You are now going to the fifth.