diff --git a/C286415/CMakeLists.txt b/C286415/CMakeLists.txt
new file mode 100644
index 0000000..27d3e00
--- /dev/null
+++ b/C286415/CMakeLists.txt
@@ -0,0 +1,10 @@
+cmake_minimum_required(VERSION 3.0)                                               
+set(CMAKE_CXX_STANDARD 17)                                                                           
+if(MSVC)                                                                                             
+    add_compile_options("/Zc:__cplusplus")                                                           
+endif()                                                                                              
+add_executable(P1 P1.cpp)
+add_executable(P2 P2.cpp)
+add_executable(P3 P3.cpp)
+add_executable(P4 P4.cpp)
+add_executable(P5 P5.cpp)
\ No newline at end of file
diff --git a/C286415/P1.cpp b/C286415/P1.cpp
new file mode 100644
index 0000000..2781131
--- /dev/null
+++ b/C286415/P1.cpp
@@ -0,0 +1,25 @@
+#define _CRT_SECURE_NO_WARNINGS
+#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
+#include <algorithm>
+#include <cstdio>
+using namespace std;
+int a[1010], n;
+int calc(int t)
+{
+    int sum = 0;
+    for (int i = 0; i < n; i++)
+        sum += min(abs(a[i] - t), min(abs(a[i] - (t - 1)), abs(a[i] - (t + 1))));
+    return sum;
+}
+int main()
+{
+    scanf("%d", &n);
+    for (int i = 0; i < n; i++)
+        scanf("%d", a + i);
+    int ans = 0x3f3f3f3f, ansi = -1, tmp;
+    for (int i = 2; i <= 100; i++)
+        if ((tmp = calc(i)) < ans)
+            ans = tmp, ansi = i;
+    printf("%d %d", ansi, ans);
+    return 0;
+}
diff --git a/C286415/P2.cpp b/C286415/P2.cpp
new file mode 100644
index 0000000..9d99f0f
--- /dev/null
+++ b/C286415/P2.cpp
@@ -0,0 +1,26 @@
+#define _CRT_SECURE_NO_WARNINGS
+#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
+#include <algorithm>
+#include <cstdio>
+#include <cstring>
+using namespace std;
+const int N = 2e5 + 50;
+char s[N], s2[N];
+int main()
+{
+    int n, k, ans = 0;
+    scanf("%d%d%s", &n, &k, &s);
+    for (char ch = 'a'; ch <= 'z'; ch++)
+    {
+        int cnt = 0;
+        for (int i = 0; i < k; i++) s2[i] = ch;
+        for (int i = 0; i <= n - k;)
+            if (memcmp(s + i, s2, k) == 0)
+                cnt++, i += k;
+            else
+                i++;
+        ans = max(ans, cnt);
+    }
+    printf("%d", ans);
+    return 0;
+}
diff --git a/C286415/P3.cpp b/C286415/P3.cpp
new file mode 100644
index 0000000..572cc67
--- /dev/null
+++ b/C286415/P3.cpp
@@ -0,0 +1,25 @@
+#define _CRT_SECURE_NO_WARNINGS
+#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
+#include <algorithm>
+#include <cstdio>
+using namespace std;
+using ll = long long;
+const int N = 2e5 + 50;
+ll f[N][3], M[3], mod = 1e9 + 7;
+int main()
+{
+    int n, l, r;
+    scanf("%d%d%d", &n, &l, &r);
+    f[0][0] = 1;
+    M[0] = (r / 3) - ((l - 1) / 3);
+    M[1] = ((r + 1) / 3) - ((l - 1 + 1) / 3);
+    M[2] = ((r + 2) / 3) - ((l - 1 + 2) / 3);
+    for (int i = 1; i <= n; i++)
+    {
+        f[i][0] = (f[i - 1][0] * M[0] % mod + f[i - 1][1] * M[2] % mod + f[i - 1][2] * M[1] % mod) % mod;
+        f[i][1] = (f[i - 1][1] * M[0] % mod + f[i - 1][2] * M[2] % mod + f[i - 1][0] * M[1] % mod) % mod;
+        f[i][2] = (f[i - 1][2] * M[0] % mod + f[i - 1][0] * M[2] % mod + f[i - 1][1] * M[1] % mod) % mod;
+    }
+    printf("%lld", f[n][0]);
+    return 0;
+}
diff --git a/C286415/P4.cpp b/C286415/P4.cpp
new file mode 100644
index 0000000..f9aa080
--- /dev/null
+++ b/C286415/P4.cpp
@@ -0,0 +1,13 @@
+#define _CRT_SECURE_NO_WARNINGS
+#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
+#include <algorithm>
+#include <cstdio>
+using namespace std;
+int s[10];
+int main()
+{
+    int n, m, p;
+    scanf("%d%d%d", &n, &m, &p);
+    for (int i = 1; i <= p; i++) scanf("%d", s + i);
+    return 0;
+}
diff --git a/C286415/P5.cpp b/C286415/P5.cpp
new file mode 100644
index 0000000..46bd295
--- /dev/null
+++ b/C286415/P5.cpp
@@ -0,0 +1,9 @@
+#define _CRT_SECURE_NO_WARNINGS
+#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
+#include <algorithm>
+#include <cstdio>
+using namespace std;
+int main()
+{
+    return 0;
+}
diff --git a/lanqiao/PREV/CMakeLists.txt b/lanqiao/PREV/CMakeLists.txt
index 3275e7e..24f0ecb 100644
--- a/lanqiao/PREV/CMakeLists.txt
+++ b/lanqiao/PREV/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.10) 
 set(CMAKE_CXX_STANDARD 17) 
-add_compile_options("/Zc:__cplusplus") 
-include_directories("D:\\PortableApps\\MSYS2\\mingw64\\include\\c++\\8.2.1\\x86_64-w64-mingw32") 
+add_compile_options("/Zc:__cplusplus" "/wd6031")
+include_directories("C:\\Programs\\MSYS2\\mingw64\\include\\c++\\8.3.0\\x86_64-w64-mingw32") 
 add_executable("PREV-01" "PREV-01.cpp") 
 add_executable("PREV-02" "PREV-02.cpp") 
 add_executable("PREV-03" "PREV-03.cpp")