There are 5 students who donated money. They donated 3 pieces of 1 yuan, 3 pieces of 2 yuan, 2 pieces of 5 yuan and 4 pieces of 10 yuan. The donations of these five students are different. The student who donated the most should donate the least how much?
有5位同学捐款，他们捐的钱有3张1元，3张2元，2张5元和4张10元的，这五位同学捐款数各不相同，问捐款最多的同学最少要捐款多少元？
<gadget id="calculator">3 * 1</gadget>
<output>3</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

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

<gadget id="calculator">4 * 10</gadget>
<output>40</output>

<gadget id="calculator">3 + 6 + 10 + 40</gadget>
<output>59</output>

<gadget id="calculator">59 - 20 - 15 - 3</gadget>
<output>21</output>

<result>21</result>