#include <bits/stdc++.h>
using namespace std;

int n, t;
int a[100];
bool final = false;

void ktao() {
    for (int i = 1; i <= n; i++)
        a[i] = 0;
}

void sinh() {
    int i = n;
    while (i >= 1 && a[i] == 1) {
        a[i] = 0;
        i--;
    }

    if (i == 0)
        final = true;
    else
        a[i] = 1;
}

bool check() {
    int dem = 0;

    for (int i = 1; i <= n; i++)
        dem += a[i];

    return dem == t;
}

int main() {
    cin >> n >> t;

    ktao();

    int cnt = 0;

    while (!final) {
        if (check())
            cnt++;

        sinh();
    }

    cout << cnt;
}