The students went to visit the "70th Anniversary of the Victory of the Chinese War of Resistance Against Japanese Aggression" photo exhibition. 163 people went to the third grade, 142 people went to the fourth grade, and 137 people went to the fifth grade. The sixth grade went to 158 people. How many people went to the four grades?
同学们去参观"中国抗日战争胜利七十周年"图片展．三年级去了163人，四年级去了142人，五年级去了137人．六年级去了158人．四个年级一共去了多少人？
<gadget id="calculator">163 + 142 + 137 + 158</gadget>
<output>600</output>

<result>600</result>