//【日期】黑色星期五
#include "stdio.h"
#include
#include "math.h"
extern int a;
int fa(int b) //判断为星期几的函数,返回值x
{int c=13,x,y=0;
if(b>12||b<1){
printf("month is error.\n"); goto out; }
if(a<=1900){
printf("year is error.\n"); goto out; }
if(((b==1||b==3||b==5||b==7||b==8||b==10||b==12)&&c>31)||(((a%4==0&&a%100!=0)||(a%400==0))&&b==2&&c>29)||((a%4!=0||a%100==0)&&c>28)||((b==6||b==4||b==9||b==11)&&c>31)||(c<1)){
printf("day is error.\n"); goto out; }
switch(b)
{ case 1:x=c%7+1;break;
case 2:x=(31+c)%7+1;break;
case 3:x=(31+28+c)%7+1;break;
case 4:x=(31+28+31+c)%7+1;break;
case 5:x=(31+28+31+30+c)%7+1;break;
case 6:x=(31+28+31+30+31+c)%7+1;break;
case 7:x=(31+28+31+30+31+30+c)%7+1;break;
case 8:x=(31+28+31+30+31+30+31+c)%7+1;break;
case 9:x=(31+28+31+30+31+30+31+31+c)%7+1;break;
case 10:x=(31+28+31+30+31+30+31+31+30+c)%7+1;break;
case 11:x=(31+28+31+30+31+30+31+31+30+31+c)%7+1;break;
case 12:x=(31+28+31+30+31+30+31+31+30+31+30+c)%7+1;break;
}
if(a>2013)x+=(a-2013)/4+(a-2013);
if(a<2013) {
x-=(2016-a)/4+(2013-a)-7;
x+=7*((2015-x)/7);
}
if(x>=7)x=x%7;
out:
return x;
}
//主函数判断某一年的13号是不是为星期五
int main()
{
int fa(int b) ;
int i=0,j[10],b,s;
scanf("%d",&a);
for(b=1;b<13;b++){
if(fa(b)==5){
j[i]=b;
i++;
}
}
s=i;
printf("There are %d Black Fridays in year %d.\n",i,a);
printf("They are:\n");
for(i=0;i<s;i++){
printf("%d/%d/13\n",a,j[i]);
}
}