Vologda 9-11 2023. B

#include <bits/stdc++.h>

#define ll long long
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define watch(x) cout << (#x) << " : " << x << '\n'
#define boost ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

using namespace std;

const int N = 33;
ll dp[N][N][N][N];

void solve() {
    int n, k;
    cin >> n >> k;

    dp[0][0][0][0] = 1;
    for (int i = 1; i <= n; i++) {
        for (int a = 0; a <= k; a++)
            for (int b = 0; b <= k; b++)
                for (int c = 0; c <= k; c++) {
                    if (a + 1 <= k) dp[i][a + 1][b][c] += dp[i-1][a][b][c];
                    if (b + 1 <= k) dp[i][a][b + 1][c] += dp[i-1][a][b][c];
                    if (c + 1 <= k) dp[i][a][b][c + 1] += dp[i-1][a][b][c];
                }
    }

    ll ans = 0ll;
    for (int a = 0; a <= k; a++)
        for (int b = 0; b <= k; b++)
            for (int c = 0; c <= k; c++)
                ans += dp[n][a][b][c];

    cout << ans << '\n';
}

main() {
    boost;
    solve();
    return 0;
}