C++ :

#include <iostream>
using namespace std;

int main() {
   int year, month;
   cin >> year >> month;

   int daysInMonth = 0;
   if (month == 2) {
      daysInMonth = ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0) ? 29 : 28;
   } else {
      daysInMonth = ((month == 4) || (month == 6) || (month == 9) || (month == 11)) ? 30 : 31;
   }

   cout <<  daysInMonth << endl;
   return 0;
}