There are 50 people attending a party, 30 men and 20 women. Men and men shake hands once each, women and women shake hands once each, and men and women do not shake hands. How many times did they shake hands in total?
某次聚会共有50人参加，男士30人，女士20人．男士与男士每人都相互握1次手，女士与女士每人都握1次手，男士与女士之间不握手．他们一共握了多少次手？
<gadget id="calculator">29 + 1</gadget>
<output>30</output>

<gadget id="calculator">29 / 2</gadget>
<output>29/2 = around 14.5</output>

<gadget id="calculator">30 * (29/2)</gadget>
<output>435</output>

<gadget id="calculator">19 + 1</gadget>
<output>20</output>

<gadget id="calculator">19 / 2</gadget>
<output>19/2 = around 9.5</output>

<gadget id="calculator">20 * (19/2)</gadget>
<output>190</output>

<gadget id="calculator">435 + 190</gadget>
<output>625</output>

<result>625</result>