diff --git a/src/sheet04.cpp b/src/sheet04.cpp
index e099105..65a1e9f 100644
--- a/src/sheet04.cpp
+++ b/src/sheet04.cpp
@@ -1,19 +1,21 @@
 #include <cstddef>
 #include <array>
 #include <initializer_list>
+#include <cmath>
 class vec
 {
     private:
-    unsigned size;
+    const double nan = std::nan("");
+    unsigned vec_size;
     double *vector;
     public:
-    vec(size_t size) : size(size), vector(new double[size]) {}
-    vec(size_t size, double ival) : size(size), vector(new double[size])
+    vec(size_t size) : vec_size(size), vector(new double[size]) {}
+    vec(size_t size, double ival) : vec_size(size), vector(new double[size])
     {
         for(size_t i=0; i<size;++i) { vector[i]=ival; }
     }
 
-    vec(std::initializer_list<double> ilist) : size(ilist.size()), vector(new double[size]) {
+    vec(std::initializer_list<double> ilist) : vec_size(ilist.size()), vector(new double[vec_size]) {
         size_t i = 0;
         for(std::initializer_list<double>::iterator itr = ilist.begin(); itr!=ilist.end();++itr)
         {
@@ -21,12 +23,55 @@ class vec
         }
     }
 
-    ~vec() {delete[] vector; }
-    vec(const vec &m) : vector(new double[m.size])
+    ~vec() {delete[] vector;}
+    vec(const vec &m) : vec_size(m.vec_size), vector(new double[vec_size])
     {
-        for(size_t i=0; i<m.size;++i)
+        for(size_t i=0; i<vec_size;++i)
         {
             vector[i] = m.vector[i];
         }
     }
+
+    vec& operator= (const vec &m)
+    {
+        if(this!=&m)
+        {
+            vec_size = m.vec_size;
+            delete[] vector;
+            vector = new double[vec_size];
+
+            for(size_t i = 0; i<vec_size; ++i)
+            {
+                vector[i] = m.vector[i];
+            }
+        }
+        return *this;
+    }
+
+    vec(vec &&m) : vec_size(m.vec_size), vector(new double[vec_size])
+    {
+        vector = std::move(m.vector);
+    }
+
+    vec& operator= (vec &&m)
+    {
+        vec_size = m.vec_size;
+        vector = std::move(m.vector);
+        return *this;
+    }
+
+    size_t size()
+    {
+        return vec_size;
+    }
+
+    double& operator[] (size_t idx)
+    {
+        if(idx>vec_size)
+        {
+            return nan;
+        }
+
+        return vector[idx];
+    }
 };
\ No newline at end of file