interface I1 { void f(); }
interface I2 { int f(int i); }
interface I3 { int f(); }
interface I4 { int f(); }
interface I5 extends I1, I2 {}
//! interface I6 extends I1, I3 {}

class C { public int f() { return 1; } }

class C2 implements I1, I2 {
  public void f() {}
  public int f(int i) { return 1; } 
}

class C3 extends C implements I2 {
  public int f(int i) { return 1; } // overloaded
}

class C4 extends C implements I3 {
  // Identical, no problem:
  public int f() { return 1; } // overriden
}

class C5 extends C implements I3, I4 {
	//public int f() {return 5;}
}

// Methods differ only by return type:
//! class C5 extends C implements I1 {}

public class InterfaceCollision {
	public static void main(String args[]) {
		int i = new C5().f();
		System.out.println(i);
	}
}