#include <stdio.h>

// 基准日期：2004年5月2日（星期日）
#define BASE_YEAR 2004
#define BASE_MONTH 5
#define BASE_DAY 2

// 闰年判断：是闰年返回1，否则返回0
int is_leap_year(int year)
{
    return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
}

// 获取指定年份和月份的天数
int get_month_days(int year, int month)
{
    int month_days[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    if (month == 2 && is_leap_year(year))
    {
        return 29;
    }
    return month_days[month];
}

// 计算从"年1月1日"到"年-月-日"的总天数
int days_from_year_start(int year, int month, int day)
{
    int total = 0;
    for (int m = 1; m < month; m++)
    {
        total += get_month_days(year, m);
    }
    total += day;
    return total;
}

// 计算两个日期之间的天数差（date2 - date1，date2需晚于date1）
int calculate_days_diff(int year1, int month1, int day1, 
                        int year2, int month2, int day2)
{
    int diff = 0;

    // 同年直接相减
    if (year1 == year2)
    {
        int days_to_date1 = days_from_year_start(year1, month1, day1);
        int days_to_date2 = days_from_year_start(year2, month2, day2);
        return days_to_date2 - days_to_date1;
    }

    // 不同年：分段计算
    int total_days_year1 = is_leap_year(year1) ? 366 : 365;
    int days_to_date1 = days_from_year_start(year1, month1, day1);
    int days_left_in_year1 = total_days_year1 - days_to_date1;

    for (int y = year1 + 1; y < year2; y++)
    {
        diff += is_leap_year(y) ? 366 : 365;
    }

    int days_to_date2 = days_from_year_start(year2, month2, day2);
    diff += days_left_in_year1 + days_to_date2;

    return diff;
}

int zeller_calc_weekday(int year, int month, int day)
{
    int y, c, m, d;
    if (month < 3)
    {
        m = month + 12;
        y = year - 1;
    }
    else
    {
        m = month;
        y = year;
    }
    c = y / 100;
    y = y % 100;
    d = day;

    int w = (y + y/4 + c/4 - 2*c + (26*(m+1))/10 + d - 1) % 7;
    if (w < 0)
        w += 7;
    
    w = w % 7;
    return w;
}

int main(void)
{
    int target_year, target_month, target_day;
    // 星期映射表：索引0=星期日，1=星期一...6=星期六
    char *weekdays[] = {"星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"};
    
    while(1)
    {
        printf("依次输入 年 月 日（需晚于%d年%d月%d日）：", BASE_YEAR, BASE_MONTH, BASE_DAY);
        scanf("%d%d%d", &target_year, &target_month, &target_day);

        // 输入合法性校验
        if (target_year < BASE_YEAR)
        {
            printf("年份应在%d年及之后！\n", BASE_YEAR);
            continue;
        }
        if (target_month < 1 || target_month > 12)
        {
            printf("月份输入错误，请输入1-12之间的数字！\n");
            continue;
        }
        int days_of_month = get_month_days(target_year, target_month);
        if (target_day < 1 || target_day > days_of_month)
        {
            printf("%d年%d月没有%d日！\n", target_year, target_month, target_day);
            continue;
        }
        if (target_year == BASE_YEAR)
        {
            if (target_month < BASE_MONTH || 
                (target_month == BASE_MONTH && target_day < BASE_DAY))
            {
                printf("日期需晚于%d年%d月%d日！\n", BASE_YEAR, BASE_MONTH, BASE_DAY);
                continue;
            }
        }

        // 计算天数差
        int total_days = calculate_days_diff(BASE_YEAR, BASE_MONTH, BASE_DAY,
                                            target_year, target_month, target_day);
        
        // 用蔡勒公式计算星期几
        int weekday = zeller_calc_weekday(target_year, target_month, target_day);

        // 输出结果
        printf("%d年%d月%d日，距%d年%d月%d日共%d天\n", 
               target_year, target_month, target_day,
               BASE_YEAR, BASE_MONTH, BASE_DAY, total_days);
        // 显示星期几
        printf("%d年%d月%d日 是 %s\n", target_year, target_month, target_day, weekdays[weekday]);

        printf("------------------------------------------------------\n");
    }
        
    return 0;
}