~cpp 

#include<iostream>
using namespace std;
int pa(int x, int y); //파스칼의 삼각형 
int main()
{
	int a,b;
	while(cin>> a >> b)
	{
		cout<<pa(a, b)<<endl ;
	}
	
	return 0;
}
	
int pa(int x, int y)
{
	return (x<=2 || x==y || y==1 ) ? 1 : pa(x-1,y-1) + pa(x-1,y);
}