Sample Count Day in month C++

code :
================

#include<iostream.h>
void main()
{
int day,month,year;
cout<<"input month:";
cin>>month;
cout<<"input year:";
cin>>year;
switch(month)
{
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:day =31;break;
case 4:
case 6:
case 9:
case 11:day=30;break;
case 2:if(year%4==0)day=29;
else day=28; break;

cout<<day;
cout<<"This month is:"<<day<<"day";
defaul:cout<<"Please Try Again";
}
if(month>=1&&month<=12)

cout<<day;
}