C :

#include<stdio.h>
main()
{
	int year,month;
	scanf("%d,%d",&year,&month);
	switch(month)
	{
		case 1:
		case 3:
		case 5:
		case 7:
		case 8:
		case 10:
		case 12:
			printf("31\n");
			break;
		case 2:
			if((year%4 == 0 && year %100 != 0)||(year %400 == 0))
				printf("29\n");
			else
				printf("28\n");
			break;
		case 4:
		case 6:
		case 9:
		case 11:
			printf("30\n");
			break;
	}
	return 0;
}

C++ :

#include<bits/stdc++.h>
using namespace std;
int y,s,m;
int main()
{
	scanf("%d,%d",&y,&m);
	if(y%100==0)
		y%400?s=0:s=1;
	else
		y%4?s=0:s=1;
	switch(m)
	{
		case 1:cout<<31;break;
		case 2:cout<<28+s;break;
		case 3:cout<<31;break;
		case 4:cout<<30;break;
		case 5:cout<<31;break;
		case 6:cout<<30;break;
		case 7:cout<<31;break;
		case 8:cout<<31;break;
		case 9:cout<<30;break;
		case 10:cout<<31;break;
		case 11:cout<<30;break;
		case 12:cout<<31;break;
	}	
	return 0;
}