Among the 143 natural numbers from 1 to 143, how many natural numbers are relatively prime to 143?
在1到143这143个自然数中，与143互质的自然数共有多少个．
<gadget id="calculator">13 - 1</gadget>
<output>12</output>

<gadget id="calculator">143 - 11 - 12</gadget>
<output>120</output>

<result>120</result>