diff --git a/arvutaja.class b/arvutaja.class
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diff --git a/arvutaja.java b/arvutaja.java
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+public class arvutaja{
+  public static void main(String[] args){
+    liides ruutjuureArvutaja = new kodutoo();
+    System.out.println("Ruutjuur arvust 100 on: "+ ruutjuureArvutaja.f(100));
+  }
+}
diff --git a/kodutoo.class b/kodutoo.class
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diff --git a/kodutoo.java b/kodutoo.java
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+public class kodutoo implements liides{
+  public double f(double n){
+    return Math.sqrt(n);
+  }
+}
diff --git a/liides.class b/liides.class
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diff --git a/liides.java b/liides.java
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+public interface liides{
+  public double f(double n);
+}