C :

#include <stdio.h>
void main()
{
	int year,month,day;
	scanf("%d%d",&year,&month);
	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&&year%100!=0||year%400==0)
				day=29;
			else
				day=28;	
	}
	printf("%d\n",day);	
}

C++ :

#include<iostream>
using namespace std;
int main()
{
int y;
cin>>y;
if(y%4==0&&y%100!=0||y%400==0)
cout<<"29"<<endl;
else cout<<28<<endl;
}

Pascal :

var
  year,day,month:integer;
begin
  readln(year,month);
  case month of
    1,3,5,7,8,10,12:day:=31;
    4,6,11:day:=30;
    2:if (year mod 4=0) and (year mod 100 <> 0) or (year mod 400=0) then
      day:=29
      else day:=28;
  end;
  write(day);
end.