Фибоначи

package tasks3;

public class Fibonacci {
    public static int fib(int n) {
        if (n <= 1) {
            return n;
        }
        int previous = 0, next = 1, sum = 0;
        for (int i = 1; i <= n; i++) {
            previous = next;
            next = previous + (sum - previous);
            sum = previous + next;
        }
        return sum;
    }

    public static void main(String[] args) {
        System.out.println(fib(3));
    }
}