diff --git a/app/src/test/java/sorting/StudentGroupComparator.java b/app/src/test/java/sorting/StudentGroupComparator.java
index 3d40be4..b1efd93 100644
--- a/app/src/test/java/sorting/StudentGroupComparator.java
+++ b/app/src/test/java/sorting/StudentGroupComparator.java
@@ -5,7 +5,7 @@ import java.util.Comparator;
 public class StudentGroupComparator implements Comparator<Student> {
 
     @Override
-    public int compare(Student s1, Student s2) {
+    public String compare(Student s1, Student s2) {
         return Integer.compare(s1.getGroupNumber(), s2.getGroupNumber());
     }
-}
\ No newline at end of file
+}