import java.util.Scanner; import java.math.BigInteger; import java.util.Scanner; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); while (scanner.hasNext()) { int stepCount = scanner.nextInt(); System.out.println(climeStep(new BigInteger(String.valueOf(stepCount)))); } } public static BigInteger climeStep(BigInteger stepCount) { if (stepCount.intValue() == 1) { return new BigInteger("1"); } if (stepCount.intValue() == 2) { return new BigInteger("2"); } BigInteger step[] = new BigInteger[stepCount.intValue()]; step[0] = new BigInteger("1"); step[1] = new BigInteger("2"); for (int i = 2; i < stepCount.intValue(); i++) { step[i] = step[i - 1].add(step[i - 2]); } return step[stepCount.intValue() - 1]; } }