这怎么输不出28
#include<iostream>
using namespace std;
int main()
{
int a;
int b;
cin>>a>>b;
if(b==1||b==3||b==5||b==7||b==8||b==10||b==12)
cout<<31<<endl;
else if(b==4||b==6||b==9||b==11)
cout<<30<<endl;
else if(a%400==0||a%4==0&&a%100!=0;b=2)
cout<<29<<endl;
else if(a%2==1;b=2)
cout<<28<<endl;
return 0;
}