#include<stdio.h>
#include<conio.h>
#include<iostream.h>
int year[]={31,28,31,30,31,30,31,31,30,31,30,31};
int change(int mm, unsigned long yy);
int leapyear(unsigned long a);
int main()
{
    int mm,mmm;
    unsigned long yy;
    do
    {
    system("cls");
    printf("\n\tInsert Month\t: ");
    scanf("%d",&mm);
    printf("\n\tInsert Year\t: ");
    scanf("%lu",&yy);
    }
    while(mm>12||yy<1900);
    int day2,i;
    char q;
    char month[12][10]={"January","Fevruary","March","April","May","June","July","August","September","October","November","December"};
    do
    {
        system("cls");
        mmm=year[mm-1];
        if(mm==2)
        {
            if(leapyear(yy))
                mmm=29;
        }
        day2=change(mm,yy);
        if(day2==0)
        {
                   day2=7;
        }
        printf("\n\n\n\n\n\t\t\t%s, %d\n\n\n",month[mm-1],yy);
        printf("\tSat\tSun\tMon\tTue\tWed\tThu\tFri\n\n");
        for(i=1;i<day2;i++)
        {
            printf("\t ");
        }
        for(i=1;i<=mmm;i++)
        {
            printf("\t%d",i);
            if(day2>6)
            {
                printf("\n");
                day2=1;
                continue;
            }
            day2++;
        }
        printf("\n\n\n\n\n\n\n\nh - Help");
        q=getch();
        if(q=='s'&&yy==1900)
        continue;
        if(q=='a'&&yy==1900&&mm==1)
        continue;
        switch(q)
        {
        case 'w':
            yy++;
            break;
        case 'a':
            if(mm==1)
            {
                mm=12;
                yy--;
            }
            else
            mm--;
            break;
        case 's':
            yy--;
            break;
        case 'e':
             system("cls");
             do
             {
                  printf("\n\tInsert Month\t: ");
                  scanf("%d",&mm);
                  printf("\n\tInsert Year\t: ");
                  scanf("%d",&yy);
             }
             while(mm>12||yy<1900);
             break;
        case 'd':
            if(mm==12)
            {
                mm=1;
                yy++;
            }
            else
            {
                mm++;
            }
            break;
        case 'h':
             system("cls");
             printf("\n\nw - Next year, same month\ns - Previous year, same month\na - Same year, previous month\nd - Same year, next month\ne - Jump to date\nAny other key to exit\n\nPress any key to go back to calender view");
             getch();
             break;
        default:
            return 0;
        }
    }
    while(1);
}
int change(int mm, unsigned long yy)
{
    int day1=3,month1=1;
    unsigned long year1=1900;
    int i;
    for(;!(month1==mm&&year1==yy);)
    {
        day1+=year[month1-1];
        if(month1==2&&leapyear(year1))
        {
            day1++;
        }
        day1%=7;
        month1++;
        if(month1>12)
        {
            month1=1;
            year1++;
        }
    }
    return day1;
}
int leapyear(unsigned long a)
{
    if( (a%400==0) || (a%4==0&&a%100!=0) )
    {
        return 1;
    }
    return 0;
}