Program to print specific date

#include<stdio.h>

#include<conio.h>

void main()

{

 int dd,mm,yy,i,a,a1,a2,b,b1,b2,d=0,sm=0;

 clrscr();

 printf("enter date(DD/MM/YYYY):");

 scanf("%d%d%d",&dd,&mm,&yy);

 if(mm>12 || dd>31)

   printf("you entered wrong date");

 else

   {

    yy=yy-1;

    a=yy%400;

    b=yy/400;

    a1=a%100;

    b1=a/100;

    a2=a1/4;

    b2=a1-a2;

    for(i=1;i<mm;i++)

     {

      if(i==2)

       {

                if((yy+1)%4==0)

                 d=d+29;

                else

                 d=d+28;

       }

      else if(i==1||i==3||i==5||i==7||i==8||i==10||i==12)

       d=d+31;

      else

       d=d+30;

     }

    sm= b*0+b1*5+a2*2+b2*1+d+dd;

    sm=sm%7;

    printf("according to entered date day is ");

    switch(sm)

     {

      case 0: printf("sunday"); break;

      case 1: printf("monday"); break;

      case 2: printf("tuesday"); break;

      case 3: printf("wednesday"); break;

      case 4: printf("thursday"); break;

      case 5: printf("friday"); break;

      case 6: printf("saturday"); break;

     }

   }

 getch();

}

OUTPUT: