diff --git a/Liides.class b/Liides.class
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diff --git a/Liides.java b/Liides.java
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+++ b/Liides.java
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+public interface Liides{
+    public double y(double x);
+}
\ No newline at end of file
diff --git a/Main.class b/Main.class
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diff --git a/Main.java b/Main.java
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+++ b/Main.java
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+public class Main{
+    public static void main(String[] args){
+        Liides juur = new Ruutjuur();
+        System.out.println("Ruutjuur on " + juur.y(1296));
+    }
+}
+
+//Ruutjuur on 36.0
diff --git a/Ruutjuur.class b/Ruutjuur.class
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diff --git a/Ruutjuur.java b/Ruutjuur.java
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+++ b/Ruutjuur.java
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+public class Ruutjuur implements Liides{
+    public double y(double x){
+        return Math.sqrt(x);
+    }
+}
\ No newline at end of file