การคำนวณผลรวมแบบ Recursive

public class SumCalculator {
    static int sum(int n) {
    	// Base case: when n is the last number 1
        if (____ ____ ____) return 1;
        // Recursive step: add the current sum and call itself
        return n + ____(n-1); 
    }
    public static void main(String[] args) {
    	// start the recursive call
        System.out.println(____(5)); 
    }
}