There are 100 students in grades four, five, and six each going on a spring outing, and they are all divided into two columns (vertical rows) and march side by side. The distance between two adjacent rows of students in the fourth, fifth, and sixth grades is 1 meter, 2 meters, and 3 meters respectively, and the distance between grades is 5 meters. They walk 90 meters per minute, and it takes 4 minutes for the whole team to pass a certain bridge, so how long is the bridge in meters?
四、五、六三个年级各有100名学生去春游，都分成2列(竖排)并列行进．四、五、六年级的学生相邻两行之间的距离分别为1米、2米、3米，年级之间相距5米．他们每分钟都行走90米，整个队伍通过某座桥用4分钟，那么这座桥长多少米．
<gadget id="calculator">90 * 4</gadget>
<output>360</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<gadget id="calculator">50 - 1</gadget>
<output>49</output>

<gadget id="calculator">49 * 1</gadget>
<output>49</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">49 * 2</gadget>
<output>98</output>

<gadget id="calculator">49 * 3</gadget>
<output>147</output>

<gadget id="calculator">2 * 5</gadget>
<output>10</output>

<gadget id="calculator">49 + 98 + 147 + 10</gadget>
<output>304</output>

<gadget id="calculator">360 - 304</gadget>
<output>56</output>

<result>56</result>