#include <fstream>

using namespace std;
ifstream cin("pascal.in");
ofstream cout("pascal.out");
void pascal ( int linie ,int a[101][101] , int coloana )
{
    int n = 1;
    a[1][1] = 1;

    for ( int i = 2 ;i <= linie ; i ++)
        for ( int j = 1; j <= i ; j++ )
            a[i][j] = a[i - 1][j - 1] + a[i - 1][j];
//    for ( int i = 1 ;i <= linie ; i ++)
//        {
//            for ( int j = 1; j <= i ; j++ )
//            cout << a[i][j];
//            cout <<'\n';
//        }
    cout << a[linie][coloana];
}

int main()
{
    int  a[101][101] = {0};
    int linie , coloana ;

    cin >> linie >> coloana ;

    pascal (linie, a , coloana );
    return 0;
}