diff --git a/main.cpp b/main.cpp
index a32c127..6ec2d12 100644
--- a/main.cpp
+++ b/main.cpp
@@ -33,14 +33,6 @@ input_data() {
 }
 
 
-//int main (){
-  //  auto in = input_data();
-    //auto bins = make_histogram(in.numbers, in.bin_count);
-  //  svg_rect(50, 0, bins[0] * 10, 30);
-  //  show_histogram_svg(bins);
-
-  //  return 0;
-//}
 
 int main(){
 
diff --git a/svg.cpp b/svg.cpp
index a78fbf3..8b695c4 100644
--- a/svg.cpp
+++ b/svg.cpp
@@ -26,16 +26,36 @@ void svg_rect(double x, double y, double width, double height){
         std::cout << "<rect x='" << x << "' y='" << y << "' width='" << width << "' height='" << height << " ' stroke='#561A75' fill='#EDB1DB' ></rect>";
 }
 
+double
+get_block_width() {
+    double BLOCK_WIDTH;
+    do {
+        std::cerr << "Enter width of one historgamm block (from 3 to 30): ";
+        std::cin >> BLOCK_WIDTH;
+        if (BLOCK_WIDTH < 3) {
+                std::cerr << "The block width cannot be less than 3px. Enter the value again.\n";
+        }
+        else if (BLOCK_WIDTH > 30) {
+                std::cerr << "The block width cannot be more than 30px. Enter the value again.\n";
+        }
+
+    } while (BLOCK_WIDTH < 3 || BLOCK_WIDTH > 30);
+    return BLOCK_WIDTH;
+}
+
 void
 show_histogram_svg(const std::vector<std::size_t>& bins) {
 
+
+
     const auto IMAGE_WIDTH = 400;
     const auto IMAGE_HEIGHT = 300;
     const auto TEXT_LEFT = 20;
     const auto TEXT_BASELINE = 20;
     const auto TEXT_WIDTH = 50;
     const auto BIN_HEIGHT = 30;
-    const auto BLOCK_WIDTH = 10;
+    double BLOCK_WIDTH = get_block_width();
+
     const std::size_t MAX_ASTERISK = IMAGE_WIDTH - TEXT_WIDTH;
     svg_begin(IMAGE_WIDTH, IMAGE_HEIGHT);
     double top = 0;
diff --git a/unittest.cpp b/unittest.cpp
index 047dda5..60ef89f 100644
--- a/unittest.cpp
+++ b/unittest.cpp
@@ -2,6 +2,7 @@
 #define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
 #include "doctest.h"
 #include "histogram_internal.h"
+#include "svg_internal.h"
 
 TEST_CASE("distinct positive numbers") {
     double mini = 0;
@@ -58,3 +59,21 @@ TEST_CASE("vector with fractional numbers") {
     CHECK(mini == 2.2);
     CHECK(maxi == 2.4);
 }
+
+TEST_CASE("20") {
+    double BLOCK_WIDTH = 0;
+    BLOCK_WIDTH = get_block_width();
+    CHECK(BLOCK_WIDTH == 20);
+}
+
+TEST_CASE("4.5") {
+    double BLOCK_WIDTH = 0;
+    BLOCK_WIDTH = get_block_width();
+    CHECK(BLOCK_WIDTH == 4.5);
+}
+
+TEST_CASE("-1") {
+    double BLOCK_WIDTH = 0;
+    BLOCK_WIDTH = get_block_width();
+    CHECK(BLOCK_WIDTH == -1);
+}