Class 6.1 just formed a square team during the gymnastics competition. Xiao Wang stood in the team and ranked third from left to right, fifth from right to left, and first from front to back. 4, which number is the number from the back to the front.
6.1班在体操比赛时正好排成了一个方队，小王站在队伍的位置从左往右数排在第3个，从右往左数排在第5个，从前往后数排在第4个，从后往前数排在第多少个．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">7 - 4</gadget>
<output>3</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>