diff --git a/app/src/main/java/com/rsschool/android2021/ErrorDialogFragment.kt b/app/src/main/java/com/rsschool/android2021/ErrorDialogFragment.kt
new file mode 100644
index 0000000..49e3a73
--- /dev/null
+++ b/app/src/main/java/com/rsschool/android2021/ErrorDialogFragment.kt
@@ -0,0 +1,23 @@
+package com.rsschool.android2021
+
+import android.app.Dialog
+import android.os.Bundle
+import androidx.appcompat.app.AlertDialog
+import androidx.fragment.app.DialogFragment
+
+class ErrorDialogFragment : DialogFragment() {
+
+    public var text: String = ""
+
+    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
+        return activity?.let {
+            val builder = AlertDialog.Builder(it)
+            builder.setTitle("ERROR")
+                .setMessage(text)
+                .setPositiveButton("Ok") {
+                        dialog, id ->  dialog.cancel()
+                }
+            builder.create()
+        } ?: throw IllegalStateException("Activity cannot be null")
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/rsschool/android2021/FirstFragment.kt b/app/src/main/java/com/rsschool/android2021/FirstFragment.kt
index 2449535..6342dff 100644
--- a/app/src/main/java/com/rsschool/android2021/FirstFragment.kt
+++ b/app/src/main/java/com/rsschool/android2021/FirstFragment.kt
@@ -5,6 +5,7 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.widget.Button
+import android.widget.EditText
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 
@@ -12,6 +13,8 @@ class FirstFragment : Fragment() {
 
     private var generateButton: Button? = null
     private var previousResult: TextView? = null
+    private lateinit var minEditText: EditText
+    private lateinit var maxEditText: EditText
 
     override fun onCreateView(
         inflater: LayoutInflater,
@@ -25,18 +28,39 @@ class FirstFragment : Fragment() {
         super.onViewCreated(view, savedInstanceState)
         previousResult = view.findViewById(R.id.previous_result)
         generateButton = view.findViewById(R.id.generate)
+        minEditText = view.findViewById(R.id.min_value)
+        maxEditText = view.findViewById(R.id.max_value)
 
         val result = arguments?.getInt(PREVIOUS_RESULT_KEY)
         previousResult?.text = "Previous result: ${result.toString()}"
 
-        // TODO: val min = ...
-        // TODO: val max = ...
-
         generateButton?.setOnClickListener {
-            // TODO: send min and max to the SecondFragment
+            val min = minEditText.text.toString()
+            val max = maxEditText.text.toString()
+
+            try {
+                var minNumber = min.toInt()
+                var maxNumber = max.toInt()
+
+                if (minNumber > maxNumber) {
+                    showError("The minimum number cannot be more than the maximum!")
+                    return@setOnClickListener
+                }
+
+                (requireActivity() as? MainActivity)?.openSecondFragment(minNumber, maxNumber)
+            } catch (nfe: NumberFormatException) {
+               showError("Please enter whole numbers!")
+            }
         }
     }
 
+    private fun showError(str: String) {
+        val errorDialogFragment = ErrorDialogFragment()
+        errorDialogFragment.text = str
+        val manager = requireActivity().supportFragmentManager
+        errorDialogFragment.show(manager, "errorDialog")
+    }
+
     companion object {
 
         @JvmStatic
diff --git a/app/src/main/java/com/rsschool/android2021/MainActivity.java b/app/src/main/java/com/rsschool/android2021/MainActivity.java
index ced8ec9..d403635 100644
--- a/app/src/main/java/com/rsschool/android2021/MainActivity.java
+++ b/app/src/main/java/com/rsschool/android2021/MainActivity.java
@@ -16,14 +16,15 @@ protected void onCreate(@Nullable Bundle savedInstanceState) {
         openFirstFragment(0);
     }
 
-    private void openFirstFragment(int previousNumber) {
+    public void openFirstFragment(int previousNumber) {
         final Fragment firstFragment = FirstFragment.newInstance(previousNumber);
         final FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
-        transaction.replace(R.id.container, firstFragment);
-        // TODO: invoke function which apply changes of the transaction
+        transaction.replace(R.id.container, firstFragment).commit();
     }
 
-    private void openSecondFragment(int min, int max) {
-        // TODO: implement it
+    public void openSecondFragment(int min, int max) {
+        final Fragment secondFragment = SecondFragment.newInstance(min, max);
+        final FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
+        transaction.replace(R.id.container, secondFragment).commit();
     }
 }
diff --git a/app/src/main/java/com/rsschool/android2021/SecondFragment.kt b/app/src/main/java/com/rsschool/android2021/SecondFragment.kt
index 536fdb1..24f44a8 100644
--- a/app/src/main/java/com/rsschool/android2021/SecondFragment.kt
+++ b/app/src/main/java/com/rsschool/android2021/SecondFragment.kt
@@ -29,16 +29,17 @@ class SecondFragment : Fragment() {
         val min = arguments?.getInt(MIN_VALUE_KEY) ?: 0
         val max = arguments?.getInt(MAX_VALUE_KEY) ?: 0
 
-        result?.text = generate(min, max).toString()
+        val random = generate(min, max)
+        result?.text = random.toString()
 
         backButton?.setOnClickListener {
-            // TODO: implement back
+            (requireActivity() as? MainActivity)?.openFirstFragment(random)
         }
     }
 
     private fun generate(min: Int, max: Int): Int {
-        // TODO: generate random number
-        return 0
+        val random = (min..max).random()
+        return random
     }
 
     companion object {
@@ -47,9 +48,9 @@ class SecondFragment : Fragment() {
         fun newInstance(min: Int, max: Int): SecondFragment {
             val fragment = SecondFragment()
             val args = Bundle()
-
-            // TODO: implement adding arguments
-
+            args.putInt(SecondFragment.MAX_VALUE_KEY, max)
+            args.putInt(SecondFragment.MIN_VALUE_KEY, min)
+            fragment.arguments = args
             return fragment
         }