/* ループによるフィボナッチ数列の実現 */
class Foo {
    public static void main (String[] args) {
    	System.out.println(fib2(10));
    }

    static int fib2 (int n) {
	int previous=1, current=1;
	for (int i=2; i<=n; i++) {
	    int old_current = current;
	    current += previous;
	    previous = old_current;
	}
	return current;
    }
}