4. At the airport, there is a moving walkway that is $500 \mathrm{~m}$ long and moves at a speed of $4 \mathrm{~km} / \mathrm{h}$. Damir and Vesna stepped onto the walkway at the same time. Vesna continued walking at a speed of 6 $\mathrm{km} / \mathrm{h}$ relative to the walkway, while Damir remained standing on it. How many meters ahead of Damir was Vesna when she stepped off the walkway?