y is that farm 4 built the trail. Help Bessie by calculating the number of different assignments of trails to the farms that built them, modulo 1,000,000,007. Two assignments are considered different if there is at least one trail built by a different farm in each assignment. </span></span></div>
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<div class="problem-text" align="left"><span class="Apple-style-span" style="font-family: simsun; font-size: 14px; color: rgb(70, 70, 70); line-height: 21px; ">给出