@FunctionalInterface
interface ArithmeticFunction {
	public int calcualate(int a, int b);
}
 
public class Main {
	public static void main(String args[]) {
		ArithmeticFunction addition = (a, b) -> a + b;
		ArithmeticFunction subtraction = (a, b) -> a - b;
 
		int a = 20, b = 5;
 
		System.out.println(perform(addition, a, b));
		// or
		System.out.println(perform((x, y) -> a + b, a, b));
 
		System.out.println(perform(subtraction, a, b));
		// or
		System.out.println(perform((x, y) -> a - b, a, b));
	}
 
	static int perform(ArithmeticFunction function, int a, int b) {
		return function.calcualate(a, b);
	}
}

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