Guangming Primary School has a total of 503 students in Grades 1 to 3, including 165 students in Grade 1 and 161 students in Grade 2. How many students are there in the third grade?
光明小学一至三年级共有学生503人，其中一年级有165人，二年级有161人．三年级有学生多少人？
<gadget id="calculator">503 - 165 - 161</gadget>
<output>177</output>

<result>177</result>