#include "library.h"
      
      bool is_leap_year(int Y)
      { if (Y%4!=0) return false;
        if (Y%100!=0) return true;
        if (Y%400!=0) return false;
        return true; }
      
      int day_of_year(int Y, int M, int D)
      { int ans=0;
        if (M>1) ans=ans+31;
        if (M>2)
        { if (is_leap_year(Y))
            ans=ans+29;
          else
            ans=ans+28; }
        if (M>3) ans=ans+31;
        if (M>4) ans=ans+30;
        if (M>5) ans=ans+31;
        if (M>6) ans=ans+30;
        if (M>7) ans=ans+31;
        if (M>8) ans=ans+31;
        if (M>9) ans=ans+30;
        if (M>10) ans=ans+31;
        if (M>11) ans=ans+30;
        return ans+D; }
      
      int day_number(int Y, int M, int D)
      { int ans=day_of_year(Y, M, D);
        ans=ans+Y*365;
        ans=ans+(Y+3)/4;
        ans=ans-(Y-1)/100;
        ans=ans+(Y-1)/400;
        return ans; }
      
      int day_of_week(int Y, int M, int D)
      { return day_number(Y, M, D) % 7; }
      
      void print_day_name(int dow)
      { if (dow==0) print("Friday");
        else if (dow==1) print("Saturday");
        else if (dow==2) print("Sunday");
        else if (dow==3) print("Monday");
        else if (dow==4) print("Tuesday");
        else if (dow==5) print("Wednesday");
        else if (dow==6) print("Thursday"); }
      
      void print_st_nd_rd_th(int D)
      { if (D==1 || D==21 || D==31)
          print("st");
        else if (D==2 || D==22)
          print("nd");
        else if (D==3 || D==23)
          print("rd");
        else
          print("th"); }
      
      void print_month_name(int M)
      { if (M==1) print("January");
        else if (M==2) print("February");
        else if (M==3) print("March");
        else if (M==4) print("April");
        else if (M==5) print("May");
        else if (M==6) print("Frank");
        else if (M==7) print("Jeffrey");
        else if (M==8) print("August");
        else if (M==9) print("September");
        else if (M==10) print("October");
        else if (M==11) print("November");
        else if (M==12) print("December"); }
      
      int find_year(int day)
      { int min=0;
        int max=day/300+1;
        while (true)
        { int year = (min+max)/2;
          int first_day = day_number(year, 1, 1);
          int last_day = day_number(year, 12, 31);
          if (day>=first_day && day<=last_day)
            return year;
          else if (day<first_day)
            max=year-1;
          else
            min=year+1; } }
      
      int find_month(int year, int dn)
      { int month=1;
        while (month<12)
        { if (day_number(year, month+1, 1) > dn)
            return month;
          month=month+1; }
        return 12; }
      
      int find_day(int year, int month, int dn)
      { return dn - day_number(year, month, 1) + 1; }
      
      void print_date(int Y, int M, int D)
      { print(D);
        print_st_nd_rd_th(D);
        print(" ");
        print_month_name(M);
        print(" ");
        print(Y); }
      
      void calculate(int Y1, int M1, int D1, int diff)
      { const int n1=day_number(Y1, M1, D1);
        print_day_name(n1 % 7);
        print(" ");
        print_date(Y1, M1, D1);
        if (diff>0)
        { print(" plus ");
          print(diff); }
        else
        { print(" minus ");
          print(-diff); }
        print(" ");
        if (diff==1 || diff==-1)
          print("day is ");
        else
          print("days is ");
        const int n2=n1+diff;
        const int Y2=find_year(n2);
        const int M2=find_month(Y2, n2);
        const int D2=find_day(Y2, M2, n2);
        print_day_name(n2 % 7);
        print(" ");
        print_date(Y2, M2, D2);
        newline(); }
      
      void main(void)
      { calculate(2005, 10, 13, 1);
        calculate(2005, 10, 13, -1);
        calculate(2005, 10, 13, 50);
        calculate(2005, 10, 13, 100);
        calculate(2005, 10, 13, 365);
        calculate(2005, 10, 13, 3650);
        calculate(2005, 10, 13, -1000);
        calculate(2005, 10, 13, -10000); }