Program to find your Day of Birth given Date of Birth

//Program to find your Day of Birth given Date of Birth

#include
#include
#include

main()
{
clrscr();
int d,m,y,year,month,day,i,n;
printf("Enter how many times you want to run this program : ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
printf("Enter the date : ");
scanf("%d%d%d",&d,&m,&y);
if( d>31 || m>12 || (y<1900>=2000) )
{
printf("INVALID INPUT");
getch();
exit(0);
}
year = y-1900;
year = year/4;
year = year+y-1900;
switch(m)
{
case 1:
case 10:
month = 1;
break;
case 2:
case 3:
case 11:
month = 4;
break;
case 7:
case 4:
month = 0;
break;
case 5:
month = 2;
break;
case 6:
month = 5;
break;
case 8:
month = 3;
break;
case 9:
case 12:
month = 6;
break;
}
year = year+month;
year = year+d;
day = year%7;
switch(day)
{
case 0:
printf("Day is SATURDAY");
break;
case 1:
printf("Day is SUNDAY");
break;
case 2:
printf("Day is MONDAY");
break;
case 3:
printf("Day is TUESDAY");
break;
case 4:
printf("Day is WEDNESDAY");
break;
case 5:
printf("Day is THURSDAY");
break;
case 6:
printf("Day is FRIDAY");
break;
}
}
getch();
return 0;
}