diff --git a/contests/4contest/4.cpp b/contests/4contest/4.cpp
index e69de29..33e436c 100644
--- a/contests/4contest/4.cpp
+++ b/contests/4contest/4.cpp
@@ -0,0 +1,41 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+#include <iomanip>
+
+struct Acc {
+    double sum = 0;
+    size_t count = 0;
+
+    void operator()(double value) {
+        sum += value;
+        count++;
+    }
+};
+
+int main() {
+    std::vector<double> data;
+
+    double value;
+    while (std::cin >> value) data.push_back(value);
+
+    size_t n = data.size();
+    size_t first_cut = n / 10;
+
+    auto it_begin = data.begin() + first_cut;
+    auto it_end = data.end() - first_cut;
+
+    std::sort(it_begin, it_end);
+
+    size_t min_cut = (it_end - it_begin) / 10;
+
+    it_begin += min_cut;
+    it_end -= min_cut;
+
+    Acc acc = std::for_each(it_begin, it_end, Acc());
+
+    std::cout << std::fixed << std::setprecision(10);
+    std::cout << acc.sum / acc.count << std::endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/contests/7contest/5.cpp b/contests/7contest/5.cpp
index e30358c..88bc642 100644
--- a/contests/7contest/5.cpp
+++ b/contests/7contest/5.cpp
@@ -4,7 +4,7 @@ public:
     virtual ~Figure() {}
 };
 
-class Rectangle : Figure {
+class Rectangle : public Figure {
     int a;
     int b;
 public:
@@ -19,7 +19,7 @@ public:
     }
 };
 
-class Triangle : Figure {
+class Triangle : public Figure {
     int a;
     int b;
     int c;
@@ -33,4 +33,18 @@ public:
 
         return false;
     }
-};
\ No newline at end of file
+};
+
+// #include <cassert>
+
+// int main() {
+//     Rectangle r1(10, 5), r2(10, 2), r3(10, 5), r4(5, 10);
+//     Triangle t1(1, 2, 3);
+//     Figure* f = &r1;
+
+//     assert(!f->equals(&r2));
+//     assert(f->equals(&r3));
+//     assert(!f->equals(&r4));
+//     assert(!f->equals(&t1));
+//     assert(!f->equals(nullptr));
+// }
\ No newline at end of file
diff --git a/contests/8contest/5.cpp b/contests/8contest/5.cpp
new file mode 100644
index 0000000..f597e18
--- /dev/null
+++ b/contests/8contest/5.cpp
@@ -0,0 +1,38 @@
+#include <iostream>
+#include <chrono>
+#include <iomanip>
+#include <sstream>
+
+std::chrono::system_clock::time_point parse_date(const std::string& date_str) {
+    std::tm tm = {};
+    std::istringstream ss(date_str);
+    ss >> std::get_time(&tm, "%Y-%m-%d");
+
+    return std::chrono::system_clock::from_time_t(std::mktime(&tm));
+}
+
+int days_between(const std::chrono::system_clock::time_point& start, const std::chrono::system_clock::time_point& end) {
+    auto duration = end - start;
+
+    return std::chrono::duration_cast<std::chrono::hours>(duration).count() / 24;
+}
+
+int main() {
+    int sum = 0;
+
+    std::string date1, date2;
+    std::cin >> date1;
+
+    while (std::cin >> date2) {
+        auto start = parse_date(date1);
+        auto end = parse_date(date2);
+
+        sum += std::abs(days_between(start, end));
+
+        date1 = date2;
+    }
+
+    std::cout << sum << std::endl;
+
+    return 0;
+}
\ No newline at end of file