diff --git a/data/Integer3/1.cpp b/data/Corner/1.cpp
similarity index 94%
rename from data/Integer3/1.cpp
rename to data/Corner/1.cpp
index 6391444..0032234 100644
--- a/data/Integer3/1.cpp
+++ b/data/Corner/1.cpp
@@ -25,9 +25,7 @@ void sanity_check(sjtu::int2048 &x,sjtu::int2048 &y) {
 }
 
 signed main() {
-    // sanity check
     sjtu::int2048 x {"0000000000001145141919810"};
-    // normal test
     sjtu::int2048 y {"-1145141919810"};
 
     y += 1;
diff --git a/data/Integer3/1.out b/data/Corner/1.out
similarity index 100%
rename from data/Integer3/1.out
rename to data/Corner/1.out
diff --git a/data/Integer3/2.cpp b/data/Corner/2.cpp
similarity index 100%
rename from data/Integer3/2.cpp
rename to data/Corner/2.cpp
diff --git a/data/Integer3/2.out b/data/Corner/2.out
similarity index 100%
rename from data/Integer3/2.out
rename to data/Corner/2.out
diff --git a/data/Integer3/3.cpp b/data/Corner/3.cpp
similarity index 77%
rename from data/Integer3/3.cpp
rename to data/Corner/3.cpp
index b9b906c..b639755 100644
--- a/data/Integer3/3.cpp
+++ b/data/Corner/3.cpp
@@ -1,6 +1,6 @@
 /*
 Time: 2023-10-20
-Test: Copy constructor and assignment operator.
+Test: Copy constructor and assignment operator. Operator +,-.
 std Time: 0.00s
 Time Limit: 1.00s
 Notes: Sanity check.
@@ -18,8 +18,8 @@ void sanity_check(sjtu::int2048 &x) {
 signed main() {
     sjtu::int2048 x {"111111111111111111111111111111111111111111111111111111111111111111111111112"};
     sanity_check(x);
-    std::cout << x << '\n';
-    std::cout << -sjtu::int2048{0} << '\n';
+    std::cout << +(+(+(+x))) << '\n';
+    std::cout << - - -sjtu::int2048{0} << '\n';
     x.read("-0");
     std::cout << x << '\n';
     return 0;
diff --git a/data/Integer3/3.out b/data/Corner/3.out
similarity index 100%
rename from data/Integer3/3.out
rename to data/Corner/3.out