This is my program (Written in C++):

#include <iostream>

using namespace std;

int day(int yy,int mm)
{
    int s=0;
    if (mm==1) s=31;
    if (mm==2)
    {
           if (yy%100==0 && (yy>1918 || (yy==1918 && mm>=2)))
               {if (yy%400==0) s=29; else s=28;}
           else
               {if (yy%4==0) s=29; else s=28;}
    }
    if (mm==3) s=31;
    if (mm==4) s=30;
    if (mm==5) s=31;
    if (mm==6) s=30;
    if (mm==7) s=31;
    if (mm==8) s=31;
    if (mm==9) s=30;
    if (mm==10) s=31;
    if (mm==11) s=30;
    if (mm==12) s=31;
    return s;
}

int week(int yyyy,int mm)
{
    int i,j;long long s;
    s=1;
    if (yyyy>1918 || (yyyy==1918 && mm>=2)) j=1918; else
    j=1600;
    for (i=j;i<yyyy;i++)
       {
           if (i%100==0 && (yyyy>1918 || (yyyy==1918 && mm>=2)))
               {if (i%400==0) s=s+366; else s=s+365;}
           else
               {if (i%4==0) s=s+366; else s=s+365;}
       }
    for (i=1;i<mm;i++)
        s=s+day(yyyy,i);
    return s%7;
}

void print(int da,int wek,int dd,int yyyy,int mm)
{
     int a[7][6],i,j;
     for (i=0;i<7;i++)
         for (j=0;j<6;j++)
             a[i][j]=0;
     int x=wek,y=0,z=6;
     for (i=1;i<=da;i++)
     {
         if (yyyy==1918 && mm==2 && i==1) {i=14;x=3;}
         a[x][y]=i;
         if (x==6) {x=0;y++;} else x++;
     }
     if (a[0][5]==0 && a[6][5]==0) z--;
     if (a[0][4]==0 && a[6][4]==0) z--;
     if (a[0][3]==0 && a[6][3]==0) z--;
     for (i=0;i<7;i++)
     {
         switch (i){
                case 0:cout<<"mon";break;
                case 1:cout<<"tue";break;
                case 2:cout<<"wed";break;
                case 3:cout<<"thu";break;
                case 4:cout<<"fri";break;
                case 5:cout<<"sat";break;
                case 6:cout<<"sun";break;
                }
         for (j=0;j<z;j++)
         {
             if (a[i][j]>0 || j<z-1) cout<<" ";
             if (a[i][j]==dd) cout<<"["; else if (a[i][j]>0 || j<z-1 )cout<<" ";
             if (a[i][j]==0 && j<z-1) cout<<"  ";
             if (a[i][j]<10 && a[i][j]>0) cout<<" "<<a[i][j];
             if (a[i][j]>9) cout<<a[i][j];
             if (a[i][j]==dd) cout<<"]"; else if (a[i][j+1]>0 && j<z-1) cout<<" ";
         }
         cout<<endl;
     }
     return;
 }

int main()
{
    int dd,mm,yyyy;
    cin>>dd>>mm>>yyyy;
    print(day(yyyy,mm),week(yyyy,mm),dd,yyyy,mm);
    system("PAUSE");
    return 0;
}

I have found the diffence between before February, 1918 and after. But when the #6 test. I have wrong answer. Why?
(In February 1918, there are only 14th to 28th, Is that right?)