diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 0000000..0702d4e
Binary files /dev/null and b/.DS_Store differ
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 1dcc716..3af6c9f 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -5,6 +5,85 @@
     "vector": "cpp",
     "ostream": "cpp",
     "functional": "cpp",
-    "string": "cpp"
+    "string": "cpp",
+    "__bit_reference": "cpp",
+    "__bits": "cpp",
+    "__config": "cpp",
+    "__debug": "cpp",
+    "__errc": "cpp",
+    "__hash_table": "cpp",
+    "__locale": "cpp",
+    "__mutex_base": "cpp",
+    "__node_handle": "cpp",
+    "__nullptr": "cpp",
+    "__split_buffer": "cpp",
+    "__string": "cpp",
+    "__threading_support": "cpp",
+    "__tree": "cpp",
+    "__tuple": "cpp",
+    "array": "cpp",
+    "atomic": "cpp",
+    "bitset": "cpp",
+    "cctype": "cpp",
+    "cfenv": "cpp",
+    "chrono": "cpp",
+    "cinttypes": "cpp",
+    "clocale": "cpp",
+    "cmath": "cpp",
+    "compare": "cpp",
+    "complex": "cpp",
+    "concepts": "cpp",
+    "condition_variable": "cpp",
+    "csetjmp": "cpp",
+    "csignal": "cpp",
+    "cstdarg": "cpp",
+    "cstddef": "cpp",
+    "cstdint": "cpp",
+    "cstdio": "cpp",
+    "cstdlib": "cpp",
+    "cstring": "cpp",
+    "ctime": "cpp",
+    "cwchar": "cpp",
+    "cwctype": "cpp",
+    "deque": "cpp",
+    "exception": "cpp",
+    "forward_list": "cpp",
+    "fstream": "cpp",
+    "future": "cpp",
+    "initializer_list": "cpp",
+    "iomanip": "cpp",
+    "ios": "cpp",
+    "iosfwd": "cpp",
+    "istream": "cpp",
+    "limits": "cpp",
+    "list": "cpp",
+    "locale": "cpp",
+    "map": "cpp",
+    "memory": "cpp",
+    "mutex": "cpp",
+    "new": "cpp",
+    "numeric": "cpp",
+    "optional": "cpp",
+    "queue": "cpp",
+    "random": "cpp",
+    "ratio": "cpp",
+    "regex": "cpp",
+    "set": "cpp",
+    "sstream": "cpp",
+    "stack": "cpp",
+    "stdexcept": "cpp",
+    "streambuf": "cpp",
+    "string_view": "cpp",
+    "system_error": "cpp",
+    "thread": "cpp",
+    "tuple": "cpp",
+    "type_traits": "cpp",
+    "typeindex": "cpp",
+    "typeinfo": "cpp",
+    "unordered_map": "cpp",
+    "unordered_set": "cpp",
+    "valarray": "cpp",
+    "variant": "cpp",
+    "algorithm": "cpp"
   }
 }
\ No newline at end of file
diff --git a/abc278/a/a b/abc278/a/a
new file mode 100755
index 0000000..139f03c
Binary files /dev/null and b/abc278/a/a differ
diff --git a/abc278/a/a.cpp b/abc278/a/a.cpp
new file mode 100644
index 0000000..8e36070
--- /dev/null
+++ b/abc278/a/a.cpp
@@ -0,0 +1,29 @@
+#include <bits/stdc++.h>
+#include <stdio.h>
+using namespace std;
+
+int main(){
+  int N, K;
+  cin >> N >> K;
+
+  int A[100];
+
+  for (int i = 1; i <= N; i++)
+  {
+    cin >> A[i];
+  }
+
+  for (int j = 1; j <= K; j++)
+  {
+    for (int k = 1; k <= N - 1; k++)
+    {
+      A[k] = A[k + 1];
+    }
+    A[N] = 0;
+  }
+
+  for (int i = 1; i <= N; i++)
+  {
+    cout << A[i] << endl;;
+  }
+}
\ No newline at end of file
diff --git a/abc278/b/b b/abc278/b/b
new file mode 100755
index 0000000..52307d7
Binary files /dev/null and b/abc278/b/b differ
diff --git a/abc278/b/b.cpp b/abc278/b/b.cpp
new file mode 100644
index 0000000..7d7bda9
--- /dev/null
+++ b/abc278/b/b.cpp
@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+#include <stdio.h>
+using namespace std;
+
+int main(){
+  int H, M;
+
+  do
+  {
+    cin >> H >> M;
+  } while (H >= 24 || M >= 60);
+
+  int Time[4];
+  int newH, newM;
+
+  do
+  {
+    if (H < 10)
+    {
+      Time[0] = 0;
+      Time[1] = H;
+    } else {
+      Time[0] = H / 10;
+      Time[1] = H % 10;
+    }
+
+    Time[2] = M / 10;
+    Time[3] = M % 10;
+
+    newH = Time[0] * 10 + Time[2];
+    newM = Time[1] * 10 + Time[3];
+
+    M++;
+    if (M == 60)
+    {
+      H++;
+      M = 0;
+    }
+    if (H == 24)
+    {
+      H = 0;
+    }
+  } while (newH >= 24 || newM >= 60);
+
+  cout << H << ' ' << M - 1 << endl;
+
+  return 0;
+}
\ No newline at end of file
diff --git a/abc278/c/c b/abc278/c/c
new file mode 100755
index 0000000..a42c410
Binary files /dev/null and b/abc278/c/c differ
diff --git a/abc278/c/c.cpp b/abc278/c/c.cpp
new file mode 100644
index 0000000..27111ab
--- /dev/null
+++ b/abc278/c/c.cpp
@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main(){
+  int N, Q;
+
+  do
+  {
+    cin >> N >> Q;
+  } while (
+    N <= 2 &&
+    N >= pow(10, 9.0) &&
+    Q <= 1 &&
+    Q >= 2 * pow(10, 5.0)
+  );
+
+  set<pair<int, int> > user;
+  user.insert({3, 2});
+
+  for (int i = 0; i < Q; i++)
+  {
+    int T, A, B;
+    cin >> T >> A >> B;
+
+    switch (T)
+    {
+      case 1:
+        user.insert({ A, B });
+        break;
+      case 2:
+        user.erase({ A, B });
+        break;
+      case 3:
+        if (user.count({ A, B }) && user.count({ B, A }))
+        {
+          cout << "Yes" << endl;
+        } else
+        {
+          cout << "No" << endl;
+        }
+        break;
+      default:
+        break;
+    }
+  };
+
+  return 0;
+}
\ No newline at end of file