diff --git a/.gitignore b/.gitignore
index b2c9882..9790ecf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,5 @@
 .idea/
 
-target/
\ No newline at end of file
+target/
+
+[a-zA-Z0-9]* lista.txt
\ No newline at end of file
diff --git a/src/main/java/Overwrite.java b/src/main/java/Overwrite.java
index e35c38e..2875667 100644
--- a/src/main/java/Overwrite.java
+++ b/src/main/java/Overwrite.java
@@ -3,19 +3,52 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.regex.Pattern;
 
 public class Overwrite {
-    public static void checkIfPeselExists(File file, String firstName, String lastName, String Pesel) {
+    public static boolean checkIfPeselExists(File file, List personalData) {
         if(file.exists()) {
+            List<String> fileContent = new ArrayList<>();
+
             try {
-                List<String> fileContent = new ArrayList<>(Files.readAllLines(file.toPath(), StandardCharsets.UTF_8));
+                fileContent = new ArrayList<>(Files.readAllLines(file.toPath(), StandardCharsets.UTF_8));
             } catch (IOException ex) {
                 System.out.println(ex.getMessage());
             }
 
+            Pattern patternFirstName = Pattern.compile(personalData.get(1).toString());
+            Pattern patternLastName = Pattern.compile(personalData.get(2).toString());
+            Pattern patternPesel = Pattern.compile(personalData.get(3).toString());
+
+            boolean peselInFile = false;
+
+            for(int i = 0; i < fileContent.size(); i++) {
+                if(patternPesel.matcher(fileContent.get(i)).find() && !patternFirstName.matcher(fileContent.get(i)).find() &&
+                        !patternLastName.matcher(fileContent.get(i)).find()) {
+                    String dataToOverwrite = personalData.get(0).toString() + " " + personalData.get(1) + " "
+                            + personalData.get(2) + " " + personalData.get(3);
+                    fileContent.set(i,  dataToOverwrite);
+                    peselInFile = true;
+                }
+            }
+
+            if(peselInFile) {
+                try {
+                    Files.write(file.toPath(), fileContent, StandardCharsets.UTF_8);
+                } catch (IOException ex) {
+                    System.out.println(ex.getMessage());
+                }
+                System.out.println("Osoba o podanym PESEL-u została już wcześniej wprowadzona. Dane zostały nadpisane.");
+
+                return true;
+            }
+            else {
+                return false;
+            }
 
         } else {
             System.out.println("Problem z odczytaniem danych z pliku.");
+            return false;
         }
     }
 }
diff --git a/src/main/java/Read.java b/src/main/java/Read.java
index 6fc2d02..9c7c191 100644
--- a/src/main/java/Read.java
+++ b/src/main/java/Read.java
@@ -24,12 +24,10 @@ public class Read {
                 System.out.println("Wprowadzony PESEL jest niepoprawny.");
             }
             else {
-                boolean saved = false;
-
-                Overwrite.checkIfPeselExists(file, personalInfo.get(1), personalInfo.get(2), personalInfo.get(3));
+                boolean saved = Overwrite.checkIfPeselExists(file, personalInfo);
 
                 if(!saved) {
-                    Write.write(personalInfo, file);
+                    Write.write(file, personalInfo);
                     System.out.println("Osoba dodana do listy.");
                 }
             }
diff --git a/src/main/java/Write.java b/src/main/java/Write.java
index b1b6a62..fd66a31 100644
--- a/src/main/java/Write.java
+++ b/src/main/java/Write.java
@@ -2,7 +2,7 @@ import java.io.*;
 import java.util.List;
 
 public class Write {
-    public static void write(List data, File file) {
+    public static void write(File file, List data) {
         if(file.exists()) {
             try (BufferedWriter fileWriter = new BufferedWriter(new FileWriter(file, true))){
                 fileWriter.write(data.get(0) + " " + data.get(1)  + " " + data.get(2) + " " + data.get(3) + "\n");
@@ -10,7 +10,6 @@ public class Write {
                 e.printStackTrace();
                 return;
             }
-            System.out.println("Zapis danych do pliku zakończył się powodzeniem.");
         } else {
             System.out.println("Problem z zapisem do pliku.");
         }