这个代码在myeclipse上运行是正确的，但是在码蹄集上显示错误，为什么？怎么改？

这个代码在myeclipse上运行是正确的，但是在码蹄集上显示错误，为什么？怎么改？
import java.util.Scanner;

public class test1 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入一个日期 ");
int year = sc.nextInt();
int month = sc.nextInt();
int day = sc.nextInt();
System.out.println(Tian(year, month, day));
}

public static String Tian(int year, int month, int day) {
    String str = year + "年" + month + "月" + day + "日 ";
    int sum = 0;
    if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
        int a[] = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
        if (month > 12 || month < 1)
            return "输入的月份不正确";
        else if (day > a[month - 1] || day < 1)
            return "输入的日期不正确";
        else {
            sum = day;
            for (int i = 0; i < month - 1; i++) {
                sum = sum + a[i];
            }
        }
        str = str + "是" + year + "年第" + sum + "天";
        return str;
    } else {
        int a[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
        if (month > 12 || month < 1)
            return "输入的月份不正确";
        else if (day > a[month - 1] || day < 1)
            return "输入的日期不正确";
        else {
            sum = day;
            for (int i = 0; i < month - 1; i++) {
                sum = sum + a[i];
            }
            str = str + "是" + year + "年第" + sum + "天";
            return str;
        }
    }
}

}

题目呢，不满足要求吧