lass=content><p><font size="4">* Line 1: A single line containing the number of assignments of trails to farms, taken modulo 1,000,000,007. If no assignment satisfies the above conditions output 0.</font></p></div></div></div></div></div><div class="row"><div class="column"><h4 class="ui top attached block header">样例</h4><div class="ui bottom attached segment font-content"><div style="position: relative; overflow: hidden;"><h4>样例输入</h4><div class="ui existing segment"><pre style="margin-top:0; m