diff --git a/06IntergersDivisorsAndPrimes.tex b/06IntergersDivisorsAndPrimes.tex
index 2461030..bb02029 100644
--- a/06IntergersDivisorsAndPrimes.tex
+++ b/06IntergersDivisorsAndPrimes.tex
@@ -591,7 +591,7 @@ Mon为单位元：$\mathrm{Wed} \times \mathrm{Mon} = \mathrm{Wed}$。
 \begin{align*}
     \lvert A_i \cap A_j \rvert & = \frac{n}{p_ip_j},\ 1 \leq i < j \leq k\\
     \lvert A_h \cap A_i \cap A_j \rvert & = \frac{n}{p_hp_ip_j},\  1 \leq h < i < j \leq k\\
-    \phi(n) = \lvert \setcom{A_1} \cap \setcom{A_2} \cap \cdots \cap \setcom{A_k} & = n - \left(\frac{n}{p_1} + \frac{n}{p_2} + \cdots + \frac{n}{p_k}\right)\\
+    \phi(n) = \lvert \setcom{A_1} \cap \setcom{A_2} \cap \cdots \cap \setcom{A_k}\rvert & = n - \left(\frac{n}{p_1} + \frac{n}{p_2} + \cdots + \frac{n}{p_k}\right)\\
     & \quad + \left(\frac{n}{p_1p_2} + \cdots + \frac{n}{p_{k-1}p_k} + \frac{n}{p_kp_1}\right)\\
     & \quad - \cdots \pm \frac{n}{p_1p_2\cdots p_k}\\
     & = n\left(1 - \frac{1}{p_1}\right)\left(1 - \frac{1}{p_2}\right)\cdots \left(1 - \frac{1}{p_k}\right)