diff --git a/src/int2048.cpp b/src/int2048.cpp
index 49ec719..6feeb4c 100644
--- a/src/int2048.cpp
+++ b/src/int2048.cpp
@@ -430,7 +430,7 @@ int2048 &int2048::Multiply(const int2048 &B) {
   // 实现复合乘法逻辑
   const int2048 *pB = &B;
   if (this == &B) pB = new int2048(B);
-  if ((this->num_length == 1 && this->val[0]) ||
+  if ((this->num_length == 1 && this->val[0] == 0) ||
       (pB->num_length == 1 && pB->val[0] == 0)) {
     *this = std::move(int2048(0));
     return *this;
@@ -542,4 +542,4 @@ bool operator>=(const int2048 &A, const int2048 &B) {
   else
     return cmp <= 0;
 }
-}  // namespace sjtu
+}  // namespace sjtu
\ No newline at end of file
diff --git a/tester/cases/2.py b/tester/cases/2.py
index 5f7de6d..dbc07dd 100755
--- a/tester/cases/2.py
+++ b/tester/cases/2.py
@@ -2,10 +2,13 @@
 from os import system
 from sys import exit
 from random import randint
+import sys
 """
 this script is used to test * operator
 """
 
+sys.set_int_max_str_digits(10000000)
+
 code_cpp_pre="""
 #include<iostream>
 #include "/home/happyzym/CSWorkSpace/Proc/BigHomework/BH-int2048-2023/include/int2048.h"
@@ -22,7 +25,8 @@ def_cpp="int2048 a_0(0),a_1(0),a_2(0),a_3(0),a_4(0),a_5(0),a_6(0),a_7(0),a_8(0),
 
 
 code_python_pre="""#!/usr/bin/python3
-
+import sys
+sys.set_int_max_str_digits(10000000)
 """
 def_python="a_0,a_1,a_2,a_3,a_4,a_5,a_6,a_7,a_8,a_9=0,0,0,0,0,0,0,0,0,0"
 
@@ -32,8 +36,8 @@ opt_python=[]
 
 if True:
   for i in range(0,10):
-    val=randint(-2**31,2**31-1)
-    opt_cpp.append("a_"+str(i)+"="+str(val)+";")
+    val=randint(-10**2,10**2)
+    opt_cpp.append("a_"+str(i)+"=int2048(\""+str(val)+"\");")
     opt_python.append("a_"+str(i)+"="+str(val))
     opt_cpp.append("a_"+str(i)+".print(); puts(\"\");")
     opt_python.append("print(a_"+str(i)+")")
@@ -44,8 +48,14 @@ if True:
     bid=randint(0,9)
     cid=randint(0,9)
     op='*'
-    opt_cpp.append("a_"+str(aid)+"=a_"+str(bid)+op+"a_"+str(cid)+";")
-    opt_python.append("a_"+str(aid)+"=a_"+str(bid)+op+"a_"+str(cid))
+    bflag="+"
+    if randint(0,1)==0:
+      bflag="-"
+    cflag="+"
+    if randint(0,1)==0:
+      cflag="-"
+    opt_cpp.append("a_"+str(aid)+"=("+bflag+"a_"+str(bid)+")"+op+"("+cflag+"a_"+str(cid)+");")
+    opt_python.append("a_"+str(aid)+"=("+bflag+"a_"+str(bid)+")"+op+"("+cflag+"a_"+str(cid)+")")
     opt_cpp.append("a_"+str(aid)+".print(); puts(\"\");")
     opt_python.append("print(a_"+str(aid)+")")
     opt_cpp.append("a_"+str(bid)+".print(); puts(\"\");")
@@ -70,7 +80,7 @@ for opt in opt_cpp:
   print(opt,file=sourc_cpp)
 print(code_cpp_suf,file=sourc_cpp)
 sourc_cpp.close()
-system("g++ /tmp/2.cpp -I /home/happyzym/CSWorkSpace/Proc/BigHomework/BH-int2048-2023/include/ -L /home/happyzym/CSWorkSpace/Proc/BigHomework/BH-int2048-2023/build/src/ -lint2048 -o /tmp/2")
+system("g++ /tmp/2.cpp -I /home/happyzym/CSWorkSpace/Proc/BigHomework/BH-int2048-2023/include/ -L /home/happyzym/CSWorkSpace/Proc/BigHomework/BH-int2048-2023/build/src/ -lint2048 -g -o /tmp/2")
 system("/tmp/2 > /tmp/2_cpp.out")
 
 sourc_python=open("/tmp/2.py","w")