#include <stdio.h>

int N, S, V[30], Num;

int back(int nv)
{
        int s = 0, i;

        if (nv == N)
        {
                s = 0;
                for (i = 0; i < N; i++)
                    s += V[i];
                if (s == S) Num++;
                return;
        }
        V[nv] = V[nv-1]+1;
        back(nv+1);
        V[nv] = V[nv-1]-1;
        back(nv+1);
}

int main()
{
        freopen("1-sir.in", "r", stdin);
        scanf("%d %d", &N, &S);

        back(1);

        freopen("1-sir.out", "w", stdout);
        printf("%d\n", Num);

        return 0;
        
}